Graph traversal refers to the problem of visiting all the nodes in a graph

Graph (mathematics)

In mathematics, a graph is an abstract representation of a set of objects where some pairs of the objects are connected by links. The interconnected objects are represented by mathematical abstractions called vertices, and the links that connect some pairs of vertices are called edges...

 in a particular manner. Tree traversal

Tree traversal

In computer science, tree-traversal refers to the process of visiting each node in a tree data structure, exactly once, in a systematic way. Such traversals are classified by the order in which the nodes are visited...

 is a special case of graph traversal. In contrast to tree traversal, in general graph traversal, each node may have to be visited more than once, and a root-like node that connects to all other nodes might not exist.

Depth-first Search

A Depth-first search

Depth-first search

Depth-first search is an algorithm for traversing or searching a tree, tree structure, or graph. One starts at the root and explores as far as possible along each branch before backtracking....

 (DFS) is a technique for traversing a finite undirected graph. DFS visits the child nodes before visiting the sibling nodes, that is, it traverses the depth of the tree before the breadth. That called DFS.

Breadth-first Search

A Breadth-first search

Breadth-first search

In graph theory, breadth-first search is a graph search algorithm that begins at the root node and explores all the neighboring nodes...

(BFS) is another technique for traversing a finite undirected graph. BFS visits the sibling nodes before visiting the child nodes.