Solidity is used for implementing smart contracts which is created by the Ethereum.

• hello_world : first program of every programming language
• datatype : dicussed about the datatypes present in solidity
• counter : checks increment and decrement functionality and gas amount deducted when value is changed but when only to view no gas amount is deducted
• enumerated : Enums are user-defined data types that restrict the variable to have only one of the predefined values.
• structure : Structure are collection of different datatype and can be used inside mappings and arrays and they can themselves contain mappings and arrays.
• view_pure : view and pure are built-in functionality given solidity to save gas amount. view function declares that no state will be changed. pure function declares no state will be changed or read.
• infoGas : DO NOT RUN THIS CODE IT IS INFINITE LOOP CODE WHICH WILL DRAINED OUR ACCOUNT WRITTEN FOR TESTING PURPOSE ONLY
• ether_units : wei = 1 wei, Kwei = 1e3 wei, Mwei = 1e6 wei, Gwei = 1e9 wei, microether = 1e12 wei, milliether = 1e15 wei, ether = 1e18 wei