Dear Student,
The word "byte" is used as a unit for measurement of memory in the computers. Secondly, whever we declare some variables in our program, these belong to certain data type like int, float, char etc. Each variable declared in our program takes certain amount of memory according to its data type. For example, If we write any program and we declare some integer type variable 'sum' in our program, it will take 4 bytes in the memory. Similarly, a variable of short integer type will occupy 2 bytes in the memory.