Bitcoin mining is finding Bitcoin blocks to help secure the Bitcoin block chain. Each Bitcoin block added on top of the Bitcoin block chain makes it more secure. Each Bitcoin block has a reference to the previous Bitcoin block and thus makes a chain of Bitcoin blocks - thus the name: block chain.
What do you need to do Bitcoin mining?
Your need a recent ASIC miner to mine Bitcoin blocks. Like the Cannan A921 ASIC miner - see details here: https://canaan.io/shop/ A Cannan A921 ASIC miner mines at 20TH/s which is about 670 thousand times faster than a computer and about 34 thousand times faster than a fast GPU. So you need a recent ASIC miner to mine Bitcoin, it's pointless mining with a computer or GPU. We don't allow people to mine on the pool using computers or GPUs.
What does a Bitcoin miner actually do?
A Bitcoin miner creates a Bitcoin block header of 80 bytes, using the work it is given e.g. by a pool, and hashes it using the SHA256 hash algorithm. Within those 80 byes, there is a 4 byte value called the nonce - that it cycles from 0 to approximately 4 billion and hashes it for each nonce value. The SHA256 hash algorithm gives a pseudo-random result for each hash done. If a hash results in a difficulty value greater than or equal to the limit specified by the work it was given, it will return the information required to produce the same 80 byte block header it hashed. A difficulty value of 1 is expected to occur, on average, once every approximately 4 billion hashes attempted. If the hash result has a difficulty value greater than the Bitcoin network difficulty, then that means the miner found a Bitcoin block!
That's too complicated, got a simpler explanation?
Now if that all went completely over your head, then here's a simple example about rolling a dice that is similar to Bitcoin mining:
Bitcoin mining is like rolling a dice and hoping you get a 5 or better to win. It's random how often you will roll and get a 5 or 6, and you can't know when you will next get a 5 or 6, or exactly how many rolls it will take. On average, you will get a 5 or 6 every 3 rolls, but that's just an average of 1 in 3 after hundreds of rolls, you won't get a 5 or 6 exactly every 3 rolls, it may sometimes take a lot more or only 1 or 2 rolls. However, Bitcoin mining is like a dice with a very large number of sides so it's expected to take a large number of attempts to get what you need to win.
Back to the details:
The number of sides is actually 2256 or ~1.158x1077 - yes that's a very large number. To find a Bitcoin block you currently have a 1 in 54,632,006,628,389,932,761,088 chance (1 in 5.46x1022) of getting the result required per each single hash your miner does. However, a 20TH/s miner does 20,000,000,000,000 hashes (20x1012) every second. The Network diffculty, that determines the chance of finding a Bitcoin block, changes after every 2016 blocks are found.
So that's like never going to happen?
Actually, Bitcoin adjusts the difficulty every 2016 blocks so that, on average, one from all the miners in the world, will find a Bitcoin block every 10 minutes! And to make that sound a little better, remember that each Bitcoin block found will be a miner just like the one mentioned further up.
At the current network difficulty, a 20TH/s miner has an approximately 1 in 31616 chance of finding a block in a day.