Bitcoin exchanges are facing regularization issues and regulator are unable to decide whether bitcoin is an currency or asset. Bitcoin has gained popularity last year and most of the steemit community is aware of the fact that bitcoin comes into market with mining.
Bitcoin Mining is a process in which any device which is used to mine bitcoin must solve complex mathematical problem to find a 64 digit solution of that problem to claim 1 bitcoin. Each time a bitcoin comes into the market it becomes difficult for the machine two mine next bitcoin as compared to the last one due to various reasons.
In early days bitcoin were mined using computer as difficulty of mining was very low. As the difficulty increased computer were replaced by Graphic Processing Units (GPU) which were mostly used for gaming but know they are widely used for mining purposes of Altcoins(cryptocurrencies other than bitcoin). GPU were then replaced with ASIC miners who contained the chips that had the ability to mine bitcoin faster than GPU.