1. Arrays allow storing multiple elements of the same data type sequentially in memory. The size of an array is fixed and elements are accessed via indexes.
2. When asking a user to enter 100 integer values, it is better to store them in a single integer array rather than defining 100 separate variables, as that would be more efficient.
3. In C, arrays are declared by specifying the data type of the elements, the array name, and the number of elements inside square brackets. Individual elements can then be accessed via their index number.