The simplest way to explain what bitcoin mining is, is the following, lets put it that way, when you use your credit card to purchase anything, someone has to process the transaction, this someone is your credit card provider (visa, master card, amex, etc) the transaction is processed with there computer to verify everything, it is the exact same thing with bitcoin mining, basically you let the bitcoin network use you computer (hardware) to verify a transaction, once is done you get paid in bitcoin, the stronger you hardware is the more hash power you have, the more transactions you can process and the more money you make. Its simple :)
