An array is a powerful and simple data structure that allows storing and accessing elements of the same data type contiguously in memory. It allows random access to elements via indices and is often used to implement other data structures like stacks and queues. Key properties of arrays include all elements being the same data type and size, stored consecutively in memory so they can be randomly accessed via their positions. Arrays have many applications including solving matrix problems, databases, sorting, and as components of other data structures.