Bitcoin is a worldwide cryptocurrency and digital payment system called the first decentralized digital currency, since the system works without a central repository or single administrator. It was invented by an unknown programmer, or a group of programmers, under the name Satoshi Nakamoto and released as open-source software in 2009. The system is peer-to-peer, and transactions take place between users directly, without an intermediary. These transactions are verified by network nodes and recorded in a public distributed ledger called a blockchain.
Bitcoin was created by Satoshi Nakamoto, who published the invention on 31 October 2008 to a cryptography mailing list in a research paper called "Bitcoin: A Peer-to-Peer Electronic Cash System". Nakamoto implemented bitcoin as open source code and released in January 2009. The identity of Nakamoto remains unknown, though many have claimed to know it.
In January 2009, the bitcoin network came into existence with the release of the first open source bitcoin client and the issuance of the first bitcoins, with Satoshi Nakamoto mining the first block of bitcoins ever (known as the genesis block), which had a reward of 50 bitcoins.
One of the first supporters, adopters, contributor to bitcoin and receiver of the first bitcoin transaction was programmer Hal Finney. Finney downloaded the bitcoin software the day it was released, and received 10 bitcoins from Nakamoto in the world's first bitcoin transaction. Other early supporters were Wei Dai, creator of bitcoin predecessor b-money, and Nick Szabo, creator of bitcoin predecessor bit gold.
In the early days, Nakamoto is estimated to have mined 1 million bitcoins. Before disappearing from any involvement in bitcoin, Nakamoto in a sense handed over the reins to developer Gavin Andresen, who then became the bitcoin lead developer at the Bitcoin Foundation, the 'anarchic' bitcoin community's closest thing to an official public face.
On 6 August 2010, a major vulnerability in the bitcoin protocol was spotted. Transactions were not properly verified before they were included in the blockchain, which let users bypass bitcoin's economic restrictions and create an indefinite number of bitcoins. On 15 August, the vulnerability was exploited; over 184 billion bitcoins were generated in a transaction, and sent to two addresses on the network. Within hours, the transaction was spotted and erased from the transaction log after the bug was fixed and the network forked to an updated version of the bitcoin protocol.
On 1 August 2017 bitcoin split into two derivative digital currencies, the classic bitcoin (BTC) and the Bitcoin Cash (BCH).
Source from Bitcoin- Wikipedia
A “wallet” is basically the Bitcoin equivalent of a bank account. It allows you to receive bitcoins, store them, and then send them to others. There are two main types of wallets. A software wallet is one that you install on your own computer or mobile device. You are in complete control over the security of your coins, but they can sometimes be tricky to install and maintain. A web wallet or hosted wallet is one that is hosted by a third party. They are often much easier to use, but you have to trust the provider to maintain high levels of security to protect your coins.