This applet uses A* search to find the shortest path from start to goal on a grid map. To use the demo, select any open square as the start and another as the goal. Then click "Find Path" to see the path A* search finds.

You can also add a turn penalty if you like. Not all searches will return different paths with and without the turn penalty. But this one will: set the start square at the lower left corner and the goal at the upper right corner. Click the "Find Path" button. Now toggle the turn penalty and click "Find Path" again.