For good end-game results, the engine may need help from endgame tables

For some (many) end games, the chess engine works nice without additional end game tables. However, this is not always the case. For some end games involving a few lighter pieces, the chess engine may not find the right moves. One way to see this is if the evaluation result for a move varies heavily between the row where it was suggested, and in the analysis of the counter move in the next move.

The endgame tables are sometimes included with the software (Houdini from Chessok), or sold separately (Chessbase). These are tables which give an absolutely correct end game evaluation for all situations the tables are made for.

They are very useful in the same way as opening books are for the opening, because the chess engine is not good at "pure positional" situations.