A single linked list is a data structure that consists of a sequence of elements, called nodes. Each node contains two parts: the data it holds and a reference, or pointer, to the next node in the sequence. This structure allows for efficient insertion and deletion of elements, as these operations can be performed without reorganizing the entire list. In a single linked list, the first node is known as the head, while the last node points to a null reference, indicating the end of the list. Unlike arrays, single linked lists do not require contiguous memory allocation, making them flexible in size. However, accessing elements requires traversing the list from the head, which can be slower than direct access in arrays.