Solidity is a programming language similar to the JavaScript syntax. Solidity is enabling the implementation of smart contracts into the Ethereum Virtual Machine (EMV). The first specification of solidity was created by Gavin Wood. Solidity is beside 4 other programming languages (Serpent, LLL, Viper and Mutan) the most popular one and is currently used for programming Ethereum but as well other private and public Blockchains. 

Solidity is directly available in any Browser and requires no downloads. If people want to debug their code they have to use Remix. With solidity every individual, corporation or group is available to design its own, custom-made Blockchain solution on the basis of the Ethereum ecosystem.