^ Jump up to: a b "Bitcoin and other cryptocurrencies are useless". The Economist. 30 August 2018. Retrieved 4 September 2018. Lack of adoption and loads of volatility mean that cryptocurrencies satisfy none of those criteria. That does not mean they are going to go away (though scrutiny from regulators concerned about the fraud and sharp practice that is rife in the industry may dampen excitement in future). But as things stand there is little reason to think that cryptocurrencies will remain more than an overcomplicated, untrustworthy casino.
The first wallet program, simply named Bitcoin, and sometimes referred to as the Satoshi client, was released in 2009 by Satoshi Nakamoto as open-source software. In version 0.5 the client moved from the wxWidgets user interface toolkit to Qt, and the whole bundle was referred to as Bitcoin-Qt. After the release of version 0.9, the software bundle was renamed Bitcoin Core to distinguish itself from the underlying network.
Proof of Work is a system that requires some work from the service requester, usually meaning processing time by a computer. Producing a proof of work is a random process with low probability, so normally a lot of trial and error is required for a valid proof of work to be generated. When it comes to Bitcoins, hash is what serves as a proof of work.
In addition to lining the pockets of miners, mining serves a second and vital purpose: It is the only way to release new cryptocurrency into circulation. In other words, miners are basically "minting" currency. For example, in February of 2019, there were a little over 17.5 million Bitcoin in circulation. Aside from the coins minted via the genesis block (the very first block created by Bitcoin founder Satoshi Nakamoto himself), every single one of those Bitcoin came into being because of miners. In the absence of miners, Bitcoin would still exist and be usable, but there would never be any additional Bitcoin. There will come a time when Bitcoin mining ends; per the Bitcoin Protocol, the number of Bitcoin will be capped at 21 million. (Related reading: What Happens to Bitcoin After All 21 Million are Mined?)
"Hexadecimal," on the other hand, means base 16, as "hex" is derived from the Greek word for 6 and "deca" is derived from the Greek word for 10. In a hexadecimal system, each digit has 16 possibilities. But our numeric system only offers 10 ways of representing numbers (0-9). That's why you have to stick letters in, specifically letters a, b, c, d, e, and f.