Bitcoin Mining is a necessary process that drives the Bitcoin
Network. It was previously possible to mine bitcoins using a high
end GPU or CPU, but with the creation of SHA-256 ASICs (Application
Specific Integrated Circuits) this has changed. At this point, only
state-of-the-art ASICs are capable of mining bitcoins
efficiently.
Mining itself is a complicated process in which these machines
attempt to provide the solution to a constantly changing
cryptographic problem. The answer to this problem is changed by
every transaction that is made on the Bitcoin network. It is nearly
impossible to truly "solve" the problem efficiently, thus the
machines attempt billions, or trillions, of solutions each second
until a correct solution is found. Once this solution is found, it
is easy to prove that it is correct, even if finding the solution
itself was difficult.
The point of this is to provide security for the Bitcoin
Network, while also processing transactions, and recording them on
the blockchain. The blockchain is a public ledger which contains
the origin of every bitcoin that has ever been created, as well as
every transaction that has ever happened.
The creation of the blockchain, and the Bitcoin mining process,
solved a decades old networking problem known as "the Byzantine
General's Problem"