So I'm trying to explain the process of mining Bitcoins to my friend, but unfortunately she's too lazy to research and watch the videos I've sent her on how mining actually works. She understands the idea of decentralized digital currency and all the pros that go along with it and how they're used in exchanges, but she doesn't understand the mining aspect of it. I don't mine that hard, so I'll admit I don't even know a LOT about it... but I can't seem to explain to her in general terms what mining Bitcoins is.
Can someone help me out and explain how to tell my friend what mining is?! BTW: She does understand the concept of blocks.
Mining attempts to make blocks of transactions permanent in the sense that they can't be changed after the fact. The idea behind it is that there is a bit of space available in a block for arbitrary data. You now try to find this arbitrary data in such a way that the complete contents of this block solve a certain puzzle. This puzzle can only be solved by bruteforcing it by trying many different values for this arbitrary data. Once the right value is found, the miner broadcasts it to the network and then it is easy to check by others that the solution is correct. However, if the contents of a block change, for example because a transaction is altered, added or removed, the puzzle is changed and a solution has to be computed again.
What is the purpose then? This system prevents people from tampering with blocks that have been found. If I want to change a transaction in a previous block, I need to solve the puzzle again for the changed block contents. And all the while the network works against me to produce new blocks. So it is almost impossible to change the contents of a block after the fact. And the "deeper" the block is (that is, the more blocks that have been mined after the one I try to change), the more blocks I have to rework, since each block has a hash to the previous block in it, creating a chain of blocks.
Mining secures the network. You could see a miner as a merger between a bank security guard and an accountant. As a reward for this effort, the miner receives a reward for 25 BTC plus any fees contained in the transactions in the mined block.