Linear structure means that there is a one-to-one correspondence between nodes in the structure. Its characteristic is that the starting node and the ending node are unique. Except for the start node and the end node, all other nodes have one and only one direct predecessor node and one and only one direct successor node. This kind of storage structure includes: sequential table (array), linked list, stack structure, queue structure and so on.

Nonlinear structure also includes set, tree structure, graphic structure or network structure, which is characterized by a one-to-many or many-to-many relationship between data elements, in which set is a very loose structure.