Hoisting a concept is where variables need not be declared and initialized before using the variable. The variable declaration can happen at any place within a function, even after using it. This is known as variable hoisting. The Solidity compiler extracts all variables declared anywhere within a function and places them at the top or beginning of a function and we all know that declaring a variable in Solidity also initializes them with their respective default values. This ensures that the variables are available throughout the function.
In the following example, firstVar, secondVar, and result are declared towards the end of the function but utilized at the beginning of the function. However, when the compiler generates the bytecode for the contract, it declares all variables as the first set of instructions in a function as shown in the following screenshot:
