A linked list is a data structure that consists of a sequence of nodes, where each node contains an element of data and a reference to the next node in the list. Linked lists are often used in applications where dynamic memory allocation is required, such as the implementation of data structures like stacks, queues, and symbol tables. They can also be used to implement more advanced data structures like hash tables and binary trees. Additionally, linked lists are often used in computer networking and operating systems to implement data structures like packets and memory management.