Solidity is a statically-typed curly-braces programming language designed for developing smart contracts that run on the Ethereum Virtual Machine. Smart contracts are programs that are executed inside a peer-to-peer network where nobody has special authority over the execution, and thus they allow anyone to implement tokens of value, ownership, voting, and other kinds of logic.
This was first introduced on the Ethereum blockchain. It has since been duplicated on the chains that were forked.