From a map to a route
Once a robot has a map, whether built beforehand or in progress via SLAM, it still needs to decide how to get from where it is to where it wants to go. This is path planning, and the map is typically represented as a grid or graph, where free space is traversable and occupied cells, walls, shelving, obstacles, are not. The planner's job is to search that representation for a route from start to goal that avoids occupied space.
A* is the classic algorithm here, and conceptually it's a smart search: it explores paths that seem most promising first, using a heuristic, usually straight-line distance to the goal, to prioritize which directions look worth exploring before wasting time on dead ends. Unlike a naive search that checks every possible path exhaustively, A* focuses its effort where it's likely to pay off, guaranteeing the shortest path is found while typically exploring far fewer options than brute force would require.