1. Dijkstra's algorithm is a greedy algorithm that finds the shortest path between nodes in a graph. It maintains a priority queue of all nodes and iteratively selects the node with the smallest distance. 2. It initializes all distances as infinity except the source node which is 0. On each iteration, it selects the node with the smallest distance and updates neighboring nodes' distances if a shorter path is found. 3. The example shows running Dijkstra's on a graph from node A. It iteratively selects the closest node and updates distances until all nodes are visited and the shortest paths from A are found.