A value argument is a variable of local scope created when a function begins execution. Its initial value is set to the value of the corresponding argument in the calling function. Changing a value argument does not affect any variable in the calling function.
A variable is a programming construct that uses a certain part of RAM to represent a specific item of data that we wish to keep track of in a program. Some examples are the weight of a pumpkin or the number of cartons of milk in the inventory of a store.
A vector is a group of variables that can be addressed by their position in the group; each of these variables is called an element. A vector has a name, just like a regular variable, but the elements do not. Instead, each element has a number, corresponding to its position in the vector.
A void return type specifier in a function declaration indicates that the function in question does not return any value when it finishes executing.