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A blockchain is a digital ledger of all cryptocurrency transactions. It is constantly growing as “completed” blocks are added to it with a new set of recordings. Each block contains a cryptographic hash of the previous block, a timestamp, and transaction data. Bitcoin nodes use the block chain to differentiate legitimate Bitcoin transactions from attempts to re-spend coins that have already been spent elsewhere.

The primary purpose of mining is to allow Bitcoin nodes to reach a secure, tamper-resistant consensus. Mining is also the mechanism used to introduce Bitcoins into the system: Miners are paid any transaction fees as well as a “subsidy” of newly created coins. This both serves the purpose of disseminating new coins in a decentralized manner as well as motivating people to provide security for the system.

Bitcoin mining is so called because it resembles the mining of other commodities: it requires exertion and it slowly makes new units available to anybody who wishes to take part. An important difference is that the supply does not depend on the amount of mining. In general changing total miner hashpower does not change how many bitcoins are created over the long term.

There are different types of Bitcoin clients. Hybrid server-assisted clients like Electrum get a lot of their network information from centralized servers, but they also check the server’s results using blockchain header data. This is perhaps somewhat more secure than either server-assisted clients or header-only clients.

Bitcoin is the most widely adopted cryptocurrency.

Bitcoin has the most developer mindshare.

Bitcoin is the most research and development mindshare.

Bitcoin is the most media mindshare.

Bitcoin is the most liquid cryptocurrency.

Bitcoin has the most unit value.

Bitcoin has the most market capitalization.

Bitcoin is the most secure cryptocurrency.

Bitcoin is the most decentralized cryptocurrency.

Bitcoin is the most censorship resistant cryptocurrency.

Bitcoin is the most permissionless cryptocurrency.

Bitcoin is the most portable cryptocurrency.

Bitcoin is the most divisible cryptocurrency.

Bitcoin is the most fungible cryptocurrency.

Bitcoin is the most verifiable cryptocurrency.

Bitcoin is the most resilient cryptocurrency.

Bitcoin is the most sovereign cryptocurrency.

Disadvantages of Bitcoin over other cryptocurrencies

Bitcoin is less private than other cryptocurrencies.

Bitcoin is less anonymous than other cryptocurrencies.

Bitcoin is less flexible than other cryptocurrencies.

Bitcoin is less efficient than other cryptocurrencies.

Bitcoin is more expensive to use than other cryptocurrencies.

Bitcoin is more risky to invest in than other cryptocurrencies.

Bitcoin is less user friendly than other cryptocurrencies.

Bitcoin is less accessible than other cryptocurrencies.

Bitcoin is less likely to be adopted than other cryptocurrencies.

Bitcoin has more forks than any other cryptocurrency.

What is a 51% attack?

A 51% attack is a potential attack on the Bitcoin network whereby an organization is somehow able to control more than 50% of the network mining hash power or computing power.

If an organization is able to control more than 50% of the network mining hash power they could:

Reverse or modify transactions

Prevent new transactions from being confirmed

Double spend coins

Stop other miners from getting rewards

How could a 51% attack be prevented?

The main way to prevent a 51% attack is by having a large number of miners spread out across the globe so that no single organization or country can control more than 50% of the network hash power.

What is a blockchain fork?

A blockchain fork is a alteration of the rules of the Bitcoin protocol whereby the software used to validate new transactions is changed.

Forks can be temporary or permanent.

Temporary forks happen all the time and are not generally considered a problem. They happen when two miners produce a block at roughly the same time and the network temporarily branches into two different directions. Eventually one branch becomes longer and the other branch is abandoned.

Permanent forks are a different story. A permanent fork can happen when the software used to validate new transactions is changed in such a way that not all nodes in the network upgrade to the new software. This can lead to two different versions of the blockchain being created and maintained.

Permanent forks can be very problematical as they can lead to confusion and can even split the community.

What is a double spend?

A double spend is when someone tries to spend the same Bitcoin twice. This is a problem because it can lead to inflation.

How can double spending be prevented?

The main way double spending is prevented is by miners including transactions in blocks in the order they receive them and then verifying that each transaction is valid before including it in a block.