Bitcoin’s scripting language is simply called Script. All Bitcoin scripts are written in Script. It is a simple language that is not Turing complete, meaning it lacks several logical functions, including loops. This is done in order to ensure that no Bitcoin script can consume inordinate computing power and harm nodes on the network.
Script is used almost exclusively to lock and unlock bitcoin, not to build applications or run programs. Script’s simplicity also gives Bitcoin security and makes it easier for developers to avoid losing money while designing wallets or applications on top of Bitcoin.
All Bitcoin transactions use Script in order to define how outputs can be spent. In other words, the script of a Bitcoin transaction determines to whom the bitcoin was sent. Bitcoin has a few different scripts, with Pay-to-Public-Key-Hash being the most popular. P2PKH is a simple script which pays bitcoin to an address.
Other scripts can achieve more complex setups, such as creating multisig addresses. Bitcoin sent to a multisig address requires multiple signatures (from multiple private keys) in order to be spent.