Bitcoin miner is a hardware which bitcoin manufactures for us. After having installed some software in it, we can configure it in mining. After that, it is kept on 24 hours running. Then it generates bitcoin for us and that is our earning. In the early days of 2009, A simple computer was used for bitcoin mining. Then in 2010 and 2011. Gpu Rig was used for bitcoin mining. In 2013,a company (Bitmain) prepared a Model S1 180Gh/s by the name of Asic(application specific integrated-circuit) miner. Later on many upgrade models S2, S3, S4, S5, S7 and S9 prepared. Now latest model Antminer S9 speed is 14Th.
As the hash rate increased on bitcoin network, Bitcoin mining became slow. This process is called bitcoin difficulty. Because of bitcoin difficulty, Asic Bitcoin miner upgraded very fast..