Breadth-first_search

BFS (G, s)                  //Where G is the graph and s is the source node
    let Q be queue.
            Q.enqueue( s ) //Inserting s in queue until all its neighbour vertices are marked.

    mark s as traversed.
            while ( Q is not empty)
    //Removing that vertex from queue,whose neighbour will be visited now
    v  =  Q.dequeue( )

            //processing all the neighbours of v
            for all neighbours w of v in Graph G
               if w is not visited
                        Q.enqueue( w )             //Stores w in Q to further visit its neighbour
    mark w as visited.