What provides the ability to quickly access array elements, and why is it so efficient?

Fast access to array elements is ensured by the fact that arrays store elements in a contiguous block of memory and are indexed by integers. This allows calculating the address of any element using the formula:

element_address = start_address_of_array + index * size_of_element

Thus, access to an element by index occurs in constant time O(1), without the need for sequential traversal. This is efficient because the processor only needs to perform a simple arithmetic operation and jump to the computed address.