A data structure used in programming to allow dynamic length lists allowing quick iteration, addition and subtraction from the list. Random access is not quick, however, requiring a search of the list. There are a few variants of LinkedLists: singly-linked lists, doubly-linked lists and circular lists (which can be either singly or doubly linked).
LinkedLists work by each node merely pointing to the next node in the list, where the last node has a NullPointer. Doubly-linked lists have a previous pointer as well, allowing bi-directional iteration. A circular list has the last node pointing back to the first node. Adding and deleting nodes aren't terribly complex but require a little thinking; you need to store temporary pointers and do a little magic.
Most higher level languages have linked list constructs. For example C++ has the STL, Java has a LinkedList in its class libraries. Category:FunctionalProgrammingLanguages almost always have linked lists as built-in datatypes, the linked list is the primary datatype in LISP. If you are coding C, however, you might have to write your own.