Breadth First Search (BFS), or Traversal is an algorithm for searching on graph data structure for a node. This algorithm is useful, for example, for searching the shortest path between two nodes, and you can see how it works on example:

The main approach: for the current node, traverse all neighbors that haven’t been visited yet, and do BFS for them. Algorithm is a technique to do graph traversal.

For tracking path, use queue data structure. When you are visiting node (this is a first element in the queue), push all non-visited neighbors of it to the queue, and remove the current node. This way, you’ll traverse all the neighbors one by one.