Bitcoin with a capital B is a payment system in the same way that credit cards and Paypal are payment systems. When you see bitcoin written in lowercase, the word is referring to an actual currency such as dollars, yen, and Euros.
Whoever invented Bitcoin is basically the Banksy of finance. The currency was created in 2009 by an unknown person who goes by the alias of Satoshi Nakamoto.
While Visa, Inc. may control Visa, there is no Bitcoin, Inc. that controls bitcoin. There is no need for a middle man when it comes to bitcoin transactions. The Bitcoin network is a peer-to-peer network that created and maintains the blockchain – a type of shared transaction ledger.
A bitcoin transaction occurs when there is a transfer of value between two different Bitcoin wallets. This transaction gets included in the blockchain. The Bitcoin wallet keeps a private key (or seed) which is a secret bit of data that is used to sign the transactions. This furnishes mathematical proof that the transfer of value has occurred and that it came from the owner of the wallet.