Bitcoin is an online currency system that was invented several years ago. As opposed to monetary systems that we are used to there is no central spot administering bitcoin.
Bitcoins can be bought and traded and maintained in a depository called an electronic wallet.
Quite often bitcoins are used as a way to pay for items across the Internet not leaving a traceable path. For this reason, ransomware quite often wants payment in bitcoin.
The idea of bitcoin was to develop a money system that is not dependent on current money systems such as the US dollars. It is envisioned as a currency of the future as all our transactions move toward eth Internet.
There has never been full disclosure of the inventor of bitcoin.
When you buy stuff using bitcoin or buy bitcoins (which are virtual and not something physical) the ownership is associated with an Internet address and not with an individual. This is as opposed to using a credit or debit account to buy with on the Internet, the account belongs to a specific person.
With no centralized authority on bitcoin there is concern how managed and how safe it is so only a few people use it. Many say bitcoin or something like it is the currency of the future.