Bitcoin is a virtual or digital currency operates peer-to-peer basis without any oversight of any central banks or government, based on cryptography, blockchain technology.
Bitcoin was created as a way for people to send money over the internet. The digital currency was intended to provide an alternative payment system that would operate free of central control but can be used just like traditional currencies.
Bitcoin blockchain is a public ledger to store the transactions. Anyone with a spare computer and good internet connection can setup his/her own node. Bitcoin nodes produce a Block every 10 minutes apart depending on network hashrate.
Bitcoin transactions are transparent and visible to anyone over the internet, which makes it harder to use for criminal purpose.