Bitcoin ASIC miners perform complex calculations known as hashes, and each hash has a chance of yielding Bitcoin. The more hashes performed, the more chances the miner has of earning Bitcoin. Miners often find themselves joining forces (aka a mining pool) to increase their chances of earning Bitcoin.
ASIC Miner Profitability: https://www.asicminervalue.com/
List of ASICs: https://en.bitcoin.it/wiki/List_of_Bitcoin_mining_ASICs