An array in C is a collection of similar data items stored in contiguous memory locations. It is a variable that can store multiple values of the same data type. Arrays are used to store a fixed-size sequential collection of elements of the same type. The size and type of an array cannot be changed once it is declared. To declare an array in C, a programmer specifies the type of the elements and the number of elements required by an array. The syntax for declaring an array is `dataType arrayName. Arrays have 0 as the first index, not 1. To access an array element, refer to its index number. Array indexes start with 0. The elements of an array can be accessed using a loop. It is possible to initialize an array during declaration. Arrays make the code more optimized and clean since we can store multiple elements in a single array at once, so we do not have to write or initialize them multiple times.