Bitcoin is both a cryptocurrency and an electronic payment system. Based on Blockchain. It is the first application of Blockchain.
The Bitcoin whitepaper: https://bitcoin.org/bitcoin.pdf
Author: Satoshi Nakamoto (the real person behind this name is unknown.)
There are more Blockchain technologies like Bitcoin: Ethereum, Hyperledger, Ripple, Zcash (named altcoins – alternate coins).
Bitcoin in reality failed as payment system due to high volatility, slow transaction speed (even hours to complete a transfer). Currently (2021) used as wealth storage. At around 50k value mark it is regarded as a good investment. Elon Musk invested in the beginning of 2021 and then sold in good profit margin a part of his (company’s) Bitcoin.
As of 2021 the Bitcoin market dominance begins to fade, making way to more eco-friendly and more suitable for digital finances solutions. To more scalable and faster ecosystems, to DeFi solutions.