Bitcoin miners power the blockchain network. Transactions that are made on the blockchain must be verified by nodes, these nodes mine an algorithm in a battle of who can solve the mathematical equation first, with the winner receiving the fee. At one point in time, you could mine on a regular desktop computer, however, as time has progressed it has become harder to do this. Miners pay for computing power and electricity amongst other things.
There have been experiments with miners where they are stored, as they must be kept cool and not overheat. It has been said that people have grown vegetables in cold climates when before it was impossible due to the heat that the computers create. In general, the cheaper it is to use electricity, the more potential profit there is to be in the business of mining as it is an operational cost.