Frequently Asked Bitcoin Interview Questions

What Is Bitcoin Mining?

Bitcoin mining is analogous to the mining of gold, but its digital form. The process involves specialized computers solving algorithmic equations or hash functions. These problems help miners to confirm blocks of transactions held within the network. Bitcoin mining provides a reward for miners by paying out in Bitcoin in turn the miners confirm transactions on the blockchain.

Miners introduce new Bitcoin into the network and also secure the system with transaction confirmation. They are also rewarded network fees for when they harvest new coin and a time when the last bitcoin is found mining will continue.

Why Bother With Bitcoin?

That’s the million Dollar question, and there’s probably a ton of answers you could give yourself. Are you fascinated by money and technology? Do you want to push the boundaries of money itself and participate in one of the biggest economic experiments of the past century?

At some point you’ll hear people say “Bitcoin is great, but you’ll never use it to buy your coffee every morning”. It’s a sign they haven’t really sat down to think about what money is, or how different people around the world use it. In fact, people are already using Bitcoin to buy their morning coffee!

Are you unserved or underserved by the current international banking system because you or your family live in an emerging economy, or freelance for clients overseas? Are you under 18, or work in an industry the credit card companies or PayPal don’t approve of?

Have you ever had an account frozen for some random irregularity, or had to pay over $20 in international money transfer fees just to send your funds to a friend or loved one? Bitcoin is the perfect solution to all of those issues.

If you’re a merchant – either online or brick-and-mortar – accepting Bitcoin is faster and cheaper than credit cards, and all payments are final. Fees are lower and there’s no risk of fraudulent chargebacks.

Perhaps you think the value of Bitcoin will increase in future and want to invest in it. Or maybe you’ve been reading about the existing fiat currency/central banking and international financial system, realize something’s not quite right with it and want to place control of your money back in your own hands. Bitcoin allows you to do this.

How Is The Blockchain Different From Banking Ledgers?

Banks and accounting systems use ledgers to track and timestamp transactions. The difference is that the blockchain is completely decentralized and open source. This means that people do not have to rely on or trust the central bank to keep track of the transactions.

The peer-to-peer blockchain technology can keep track of all the transactions without the fear of having them erased or lost.

Furthermore, the blockchain, because of its open source nature, is more versatile and programmable than central banking ledgers. If programmers need new functionality on the blockchain, they can simply innovate on top of already existing software through consensus. This is difficult for central banks because of all of their regulations and central points of failure.

How Can You Buy Bitcoin?

Bitcoins can be bought from various sources. You can purchase them online using an exchange or brokerage service that will enable you to buy Bitcoin with a bank transfer using fiat currency, a credit card, and some services also offer buying opportunities using Paypal.

Bitcoin can also be purchased locally using LocalBitcoins, and from Bitcoin Teller Machines which are similar to cash ATMs that you find worldwide.

Bitcoin.com offers a recommended list of current online exchanges and brokers who sell bitcoins. You can also buy Bitcoins instantly using your credit card on Bitcoin.com (The service is provided by Simplex). Our aim is to provide the best quality services via our website so anyone can easily obtain the cryptocurrency from a wide array of respected Bitcoin buying/selling platforms.

What Is Double Spending?

Double-Spending is the act of using the same bitcoins twice. There is only a 21 million set cap on the protocol and no more can be produced. So the network protects against double spend by the verification of each recorded transaction. The blockchains ledger ensures that the transactions are finalized by its inputs confirmed by miners.

The confirmations make each unique Bitcoin and its subsequent transactions legitimate. If one tried to duplicate a transaction the original blocks deterministic functions would change showing the network that it is counterfeit and would not to be accepted.

What Is The Blockchain?

Bitcoin is dependent on the blockchain that underlies and structures the system. The blockchain is the vertebrae of the protocol and the glue that holds the network together. It is simply a vast, distributed public ledger of account. It keeps track of every transaction ever made in the network, and all transactions are timestamped and verified by network miners.

This is how it works:

miners with specialized computers compete to solve mathematical puzzles with other computers, and once they solve a puzzle they are awarded with some Bitcoin, but they also add a “block” of completed transactions to the blockchain for future viewing and verifiability.

Once a block is added to the chain the cycle repeats itself, and the computers continue to compete to solve these difficult problems. Every transaction on the blockchain is completely transparent and accounted for in its log.

Anyone can see the public keys of any transaction they want (although there are no names associated with transactions). One could go all the way back and view the very first transactions ever made on the first block ever created. This block was unironically called the Genesis Block.

Who Developed Bitcoin?

The original Bitcoin code was designed by Satoshi Nakamoto under MIT open source credentials. In 2008 Nakamoto outlined the idea behind Bitcoin in his White Paper, which scientifically described how the cryptocurrency would function.

Bitcoin is the first successful digital currency designed with trust in cryptography over central authorities. Satoshi left the Bitcoin code in the hands of developers and the community in 2010. Thus far hundreds of developers have added to the core code throughout the years.

What Is It And Why Is It Important?

Bitcoin‘s inventor, Satoshi Nakamoto, described Bitcoin as “A Peer-to-Peer Electronic Cash System” in the original 2009 Bitcoin whitepaper – the document which created the roadmap for Bitcoin. To date, this is still the most simple and accurate description.

Bitcoin is a consensus network that enables a new payment system and a completely digital money. It is the first decentralized peer-to-peer payment network that is powered by its users with no central authority or middlemen.

From a user perspective, Bitcoin is perhaps best described as ‘cash for the Internet’, but Bitcoin can also be seen as the most prominent triple entry bookkeeping system in existence.

It is also known as digital cash, cryptocurrency, an international payment network, the internet of money – but whatever you call it, Bitcoin is a revolution that is changing the way everyone sees and uses money.

The beauty of Bitcoin is that it requires no central servers or third-party clearing houses to settle transactions – all payments are peer-to-peer (P2P) and are settled in about 10 minutes – unlike credit card payments, which can take weeks or months before they’re finally settled.

All Bitcoin transactions are recorded permanently on a distributed ledger called the “blockchain” – this ledger is shared between all full Bitcoin “miners” and “nodes” around the world, and is publicly-viewable.

These miners and nodes verify transactions and keep the network secure. For the electricity they use to do this, miners are rewarded with new bitcoins with each 10-minute block (the reward is currently 12.5 BTC per block).

The Bitcoin protocol is also hard-limited to 21 million bitcoins, meaning that no more than that can ever be created. This means that no central bank, individual or government can come along and simply ‘print’ more bitcoins when it suits them. In this sense Bitcoin is a deflationary currency, and as such is likely to grow in value based on this property alone.

Bitcoin is still a cutting-edge experiment in technology and economics, and like the worldwide web in 1995, its myriad potential, purposes and applications are yet to be decided. Is it just electronic money? A foundation for smart contracts and electronic shares?

Is it underground and subversive, challenging the power of governments, or will it integrate into mainstream finance and go unnoticed? If you know the answers to any of these questions, or if you can figure out how to capitalize on them there may be many lucrative opportunities for you in the Bitcoin space.

The Bitcoin universe is changing fast and often – to stay ahead of the game it’s necessary to follow the news almost-hourly and discuss the latest events with other members of the community. Bitcoin.com exists to be a reliable information hub for beginners and industry insiders alike.

That being said, ‘staying ahead of the game’ is not a necessity if you simply wish to use Bitcoin as a currency to purchase goods and services, or wish to accept Bitcoin for transactions – something thousands of people around the world do every single day.

Can You Sell Bitcoin?

Bitcoins can be sold in various fashions. The currency can be sold online to an exchange or live in person locally. These same instances work similarly to the buying process. You can sell your Bitcoin to the exchange at the current price it’s being sold for.

More anonymously you can sell in person or use a localized 2-way ATM. ATMs can be found all over the world and these machines are mostly used for purchasing. 2-way ATMs can allow you to sell the currency. Most ATMs however only allow you to buy Bitcoin. There are also teller machines that require identification as well.

Bitcoin payments are easy to make with a wallet application and addresses. You can use a standard desktop or smartphone to transact with an individual, merchant and exchange. Addresses can be used in number form, in a QR code and contactless technology.

Transacting with Bitcoin offers lower fees than any known remittance provider and credit card service. No bank, no state, no third party can offer this low amount of fees.

Can Stores Accept Bitcoin?

Brick and mortar outlets can also accept Bitcoin. Services like Coinbase, CoinKite, and BitPay offer applications and hardware for the convenience of the store owner. Most of these businesses offer invoicing and accounting with their services. However, third party services are not required by physical merchants to accept the currency.

Individual users can also accept Bitcoin directly and handle the transactions and accounting themselves. Bitcoins can be sold in various fashions. The currency can be sold online to an exchange or live in person locally.

These same instances work similarly to the buying process. You can sell your Bitcoin to the exchange at the current price it’s being sold for.

More anonymously you can sell in person or use a localized 2-way ATM. ATMs can be found all over the world and these machines are mostly used for purchasing. 2-way ATMs can allow you to sell the currency. Most ATMs however only allow you to buy Bitcoin. There are also teller machines that require identification as well.

Bitcoin payments are easy to make with a wallet application and addresses. You can use a standard desktop or smartphone to transact with an individual, merchant and exchange. Addresses can be used in number form, in a QR code and contactless technology.

Transacting with Bitcoin offers lower fees than any known remittance provider and credit card service. No bank, no state, no third party can offer this low amount of fees.

Why Trust Bitcoin?

Bitcoin is a network operating by the three foundational principles of technological freedom: Decentralization, Open Source code, and true Peer-to-Peer technology. Bitcoin’s trust is based on the subjective valuations of human faith in mathematical algorithms, encryption and numbers. With the three pillars of technological principles Bitcoin’s blockchain is a peer-reviewed system of integrity.

Is Bitcoin Anonymous?

Participants in Bitcoin transactions are identified by public addresses – those are the long strings of around 30 characters you see in a person’s Bitcoin address, usually starting with the numerals ‘1’ or ‘3’. For every transaction, the sending and receiving addresses are publicly-viewable.

Since these numbers are virtually incomprehensible, difficult to remember without a computer and don’t contain a person’s name or identifying information, it is often claimed that Bitcoin is an “anonymous currency”. This is also often used as an argument to attack Bitcoin as a currency for illegal transactions and tax evasion.

But it’s not as simple as that. If you publish your address anywhere, it can be linked to your real-life identity.

Even if you don’t publish it, simply re-using the same address many times can show a pattern that an analyst with basic skills could link to your identity by looking at transaction times, amounts, location and regularity – and connecting it to other data sources like receipts, exchanges, and shipped items.

It’s recommended for privacy and security that you use a new address for every single transaction, and most modern wallet software is designed to do just that. But even though this increases the amount of effort and skill required to uncover your identity, it doesn’t make you 100% anonymous.

Freely available blockchain explorers and analytical tools have been used to link addresses with only single transactions to other addresses, forming a chain or pattern that eventually reveals its owner. These have been useful in investigating cases of theft at companies like Mt. Gox and Bitcoinica, but can potentially be used to identify anyone.

Due to all of this, it’s more accurate to say Bitcoin is “pseudonymous” and not anonymous. Think of it as a less memorable email address or online handle. Even if it’s not your real name, someone out there can potentially find out who the real person behind the pseudonym is.

What Can Bitcoin Do?

The Bitcoin protocol can change the financial landscape we see today. The protocol can act as a currency, voting mechanism, global identification and reputation application, a micro-tipper, crowdfunding platform, initiate trusts, wills and contracts, decentralized domain names, future markets, and basically everything the financial system of today can handle plus so much more.

The currency application is just the beginning of this evolution of world’s finances.

What Happens If I Lose My Bitcoins?

Unfortunately, since unique private keys are associated with individual Bitcoin wallets, if the keys are lost, there is ultimately no way to retrieve that key without a passcode seed or other retrieval system; and that key is required to spend those coins.

However, most modern wallets, like Mycelium, have wallet and key backups that you can build prior to storing money. This will allow you to create a new private key so that you may restore your private key on a new wallet if lost.

Who Is In Charge Of Bitcoin?

Nobody is “in charge” of Bitcoin – at least in the sense that Bitcoin is not a company or organization, has no governing body and no organizational structure. Bitcoin is simply a software protocol, like HTTP (aka the Internet and SMTP (aka email).

This has been the case since Bitcoin’s creator, the person (or persons) calling themselves Satoshi Nakamoto, released their creation into the wild in 2009. There are, however, certain groups who can exert influence over the way Bitcoin functions through various means.

Again, though, there are no individuals who can claim to speak for these groups and they contain a plethora of opinions and incentives within. Examples of such groups are: Developers: These are the people who write and maintain the software the Bitcoin network runs on.

Although Satoshi Nakamoto released the first version of Bitcoin himself in 2009, the code has since been re-written and updated by subsequent programmers.

The developers choose what updates to make to the protocol, and consider ways it can be improved. Miners: These are the people (and companies) that own the machines that generate new bitcoins and keep the network secure by validating transactions. As a result, they have the power to “vote” with their hardware and choose which Bitcoin software to support.

Developers may create and release radical revisions to the Bitcoin protocol, but they’ll have no effect unless the Bitcoin miners choose to adopt them. Users: That’s you. At the end of the day, if regular users decide Bitcoin no longer fulfils their needs, then it will have no value.

You can see the user effect in action just by looking at alternative cryptocurrencies collectively known as ‘altcoins’ – there are currently about 700 different altcoins of varying degrees of popularity. They have risen and fallen in favor as users decided whether to buy, hold, sell, or simply abandon.

Merchants have made individual decisions as to whether to accept them as payment or not. Bitcoin faces the same market conditions, and there’s no shortage of new projects claiming their protocol is superior.

So far none have knocked Bitcoin from its position as the most popular cryptocurrency, but there’s no guarantee this will always be the case. Large holders, venture capitalists and influential figures in the “Bitcoin community” could also affect Bitcoin’s future path, though their influence is less direct. And again, there is rarely a consensus of vision among them.

What Is A Bitcoin Wallet?

Like the name suggests, a Bitcoin wallet is an application that stores, sends and receives bitcoins. You can think of it like you would a leather wallet full of physical cash, and basically that’s all you need to use Bitcoin.

The most common wallets are smartphone-based, and use the device’s camera to scan QR codes to save the user from needing to copy/paste long Bitcoin addresses. Other people have desktop versions or use browser-based wallets.

To the end user the interface is similar, though the way they function and handle private keys (the ‘key’ which allow you to spend your bitcoins) and user privacy can be very different.

Some apps have features that add value to your Bitcoin-using experience, like location-based Bitcoin business guides, links to exchanges to trade in and out of fiat currencies, more secure vault storage, or the ability to hold digital tokens other than just Bitcoin, such as any number of the many altcoins on offer.

Some wallets have central servers, meaning users have to create accounts with a login name (usually an email address) and password. These are less private and (if login info and keys are not secured properly) may be vulnerable to hackers. On the upside, when a centralized wallet is used if a user forgets their password it’s usually recoverable.

Other wallets store all information and private keys on the device itself, some of which generate wallet keys from a single “seed” phrase of about 12 words. If a user remembers the seed phrase, then the wallet can be restored elsewhere if the device is lost or broken. On the downside, if you forget that seed phrase the wallet can’t be recovered.

Apart from smartphone/desktop apps you can also buy specialized hardware devices like Trezor and Ledger to keep your keys completely offline, or even print a wallet on paper to keep them as safe from hackers as possible. These are the best options for users holding large amounts of Bitcoin.

Bitcoin users now have a wide selection of wallets to choose from and features have improved vastly over the past couple of years. But with more choice comes the need for more caution: fraudulent Bitcoin wallets have begun to appear that mimic the look of popular wallets, but are actually malware that steals bitcoins.

Why Does The Bitcoin Price Move So Much?

Until Bitcoin becomes the dominant currency for payments around the world, it will be more popular among traders and price speculators.

As a result, the price is subject to the market forces of supply and demand which, at this point in time, goes hand in hand with the trends and whims of speculators – as a result, the price can move suddenly and sharply up or down in response to news events.

As a rule of thumb: if a piece of news makes Bitcoin more likely to be widely adopted, the price rises. If it places extra hurdles towards mass adoption, the price will fall.

You can track all the latest Bitcoin price movements in real time with Bitcoin.com’s data charts, and convert the price to your local currency with our instant Price Converter.

These events may be based on issues affecting the Bitcoin world only – such as a large scale hack affecting a key Bitcoin exchange, wallet or essential software which causes the price to dip. This happened after the Mt. Gox meltdown in 2014 and thefts at Bitstamp and Bitfinex, plus numerous other smaller companies.

A large market such as the EU, China, Japan or US may announce new regulations either favorable or restrictive to Bitcoin, causing the price to rise or fall respectively (when the Chinese government restricted Bitcoin exchanges’ practices in 2013, the price fell from its record high).

It may be an internal issue, such as a miners’ conference or meeting to decide changes to the Bitcoin protocol; the price sometimes dips if a block size or scaling consensus cannot be reached, or seems to be too far off.

News which affects the price may be only vaguely related to Bitcoin, or sometimes not at all. Dramatic economic/financial news like new tax policies, bank runs or bailouts, negative interest rates, stock market crashes, banking instability or government bankruptcies all suggest a new kind of asset class may be preferable, and the Bitcoin price rises.

The price sometimes fluctuates wildly for no apparent reason at all. Sudden crashes, massive increases and up/down volatility can happen and, even after the fact, traders debate over what may have caused it. A large price build-up may suddenly reverse when it hits a certain price level, at which point traders set limit orders and/or take profits. The inverse happens if the price drops too far.

Some have suggested Bitcoin can never be adopted as a regular currency while prices are so volatile. In truth, if there was a sudden rush to Bitcoin among the general public (maybe due to a crisis in a major fiat currency) the price would probably rise dramatically and then stabilize – especially if there was nothing to swap it for, or no reason to do so.

In the meantime, if you think you can predict the big movements then good luck on the trading exchanges! But be careful, it can also be inexplicable and unpredictable.

How Can I Trade Bitcoin Without An Exchange?

There are plenty of reasons to want to trade Bitcoin for fiat and other digital tokens without an exchange.

The main one is security and trust – two of the largest Bitcoin exchanges of all time, Mt. Gox and Bitfinex, have suffered catastrophic hacks in the past and lost hundreds of thousands of their users’ BTC. Not to mention the multiple other smaller exchanges that were hacked or disappeared in mysterious circumstances.

Another is privacy – exchanges these days have similar know-your-customer (KYC) requirements to banks. All this information is kept on file and, like your funds, is at risk of theft if the exchange’s security isn’t up to scratch.

Person-to-person trading is a small but growing market, with services like LocalBitcoins facilitating individual trade deals between users.

Some also use online classifieds like Craigslist or even chat groups on apps like Telegram and WeChat to indicate willingness to trade in person. Other services like BitKan have special apps designed to introduce you to online buyers who may not be in your physical location.

Be aware that, in many jurisdictions, even trading with other individuals in a private arrangement is regulated by KYC and anti money laundering (AML) laws, meaning you could be at risk if you don’t know anything about the people you’re trading with. As such, it is important to clarify your local laws before engaging in person to person trades.

Can I Make Money Mining Bitcoin?

The days where anyone could make money mining Bitcoin with a desktop computer or GPU cards are unfortunately long gone. The total computing (or “hashing”) power of the network has risen exponentially since the introduction of application-specific integrated circuits (ASICs), or machines designed specifically to solve Bitcoin’s mining proof-of-work algorithm and nothing else.

It is still possible for individual miners to make some money by purchasing their own ASIC-based equipment – however, most mining takes place in large factory-like environments with hundreds of machines, in places where energy is cheap (such as China and above the Arctic Circle).

And once your machine is superseded by a newer model a few months after purchase, its ability to compete on the network (and thus its earning potential) is greatly diminished, along with its resale value.

You also need to consider energy costs where you live. Bitcoin-mining ASIC machines run very hot and consume large amounts of electricity. You’ll need to subtract the costs of electricity and cooling from the profits you make.