Altcoins refer to all other cryptocurrencies other than Bitcoin. In recent years, the definition has expanded to coins other than Bitcoin and Ethereum since many cryptos are forked from one of the two.
Bitcoin
Cryptocurrencies like Bitcoin run on blockchains- a shared and immutable list of transactions that allows convenient tracking and recording.
Crypto wallets keep your private keys or passwords that give you access to your coins. These wallets can be custodial or non-custodial crypto wallets.
El Salvador is the first nation to adopt Bitcoin as a legal tender, which aims to expand financial inclusion. However, the nation's Bitcoin experience has had mixed results due to its low adoption rate.
Bitcoin halving will happen sometime in April 2024 and will impact the blockchain and all stakeholders involved.