The bitcoin blockchain, among many in the cryptocurrency world, is ever-evolving and highly modifiable, with changes being amended to it every single day but far less actually making it onto the blockchain itself. If you're wondering to yourself what the blockchain actually is and how it works, we've got all the information for you right here, right now.
A blockchain at its simplest is just a very secure distributed database that holds ordered records called blocks that have a timestamp attached to it and a link to a previous block (except the genesis block, which has to be coded in specially for each blockchain. Each one contains a special meaning or code inside of it in most cases, including Bitcoin's genesis block!) and cannot be modified once it is created. Blockchains are fairly recent things in the history of computing and networks, first widely used in Bitcoin.
Fun Fact: Bitcoin's blockchain reached 20GB in August 2014. The size has long since surpassed that size and is continually growing!
Blockchains were initially invented for secure data keeping and is suitable for use with records management, whether that is the storage of medical records or something as simple as dates and events. Blockchains are just like calendars, except they're nearly impervious to change and are nearly indestructible if the correct steps are taken to ensure that they cannot be modified in a way that is not intended.
Blockchains are open and are secure mainly because everybody in the world on the network is (theoretically. There are ways that the Bitcoin client and others recognize when a client is not on the right blockchain) reading the same data and blocks. It's just a decentralized database that can't be modified without everybody noticing the modifications and requires a majority consensus to change (most of the time). By storing data across thousands and even millions of devices and systems, the risks of a centralized system are virtually not present in a blockchain and every user has the same 'importance' as everybody else on the blockchain. Transactions, however, are not treated like this and in most blockchains (except for a few that use some different kind of method for transactions), the transactions with the highest fees get the priority in a block. Consensus methods vary by blockchain, but the central ideas are present in all blockchains, whether PoS or PoW. As mentioned before, a blockchain can be modified at any time with a consensus agreement and blockchains can and will vary from each other- for example, Bitcoin's block time is at an average of ten minutes, whereas Monero's block time is at an average of 2 minutes. Fluctuations do occur in blocktime, but it averages out in the long run due to different factors and the difficulty algorithms in each blockchain.
Although not all-encompassing, this guide shows you the basics of the blockchain and will tell you the essentials of what you need to know about it. Whether you're using this data for a project or just for fun, we hope this guide has helped you out and we hope you'll stick with us for more content like this in the future.