A beginners guide to chess engines

How do engines work?

Engines evaluate positions and express their evaluation as a number. 0.0 means they consider the position to be equal, 1.0 means an advantage of roughly 1 pawn. The advantage doesn't have to be materialistic, it can also be positional. Positive values mean advantage for white, negative values for black.

Engines expect both players to play the best possible moves. So a 0.0 evaluation means, the engine expects the position to be equal if both players play perfectly. That further means, that players can never really improve the evaluation in their favor. If you play the best possible move, the evaluation stays the same, otherwise it gets worse.

So, like some parents, engines are strictly deficit-oriented. In their eyes you cannot do any good, you either fulfill their expectations by being perfect, or you're getting passive aggressive annotations telling you "you were inaccurate", "you made a mistake", "you just blundered (you fool)". Frustrating, right? You won't get any credit at all for finding and playing a genius attacking move, that collapses your opponent's position. Your opponent, however, will get an earful, for allowing you to play this move.

Theoretical vs practical advantage

Don't compare yourself to computers, they're better than us all (at chess at least). There is a clear difference between a theoretical and a practical advantage. A theoretical advantage of +3.0 could be, that if you find an insane 25 move computer combination, in the end you could win a bishop. A practical advantage of +3.0 would be, there's a free bishop, take it.

So staying realistic and not trashing yourself for not finding computer lines is vital to stay sane and to keep having fun playing chess.

An example from the pros

An engine evaluation of 0.0 means nothing more than "there is a way to keep this game equal/to draw it". But it says nothing about how easy this way is. It might be a position where you practically cannot blunder at all, or it could be, that you need to find a weird 10 move computer combination to save your position.

One person, who is a master at squeezing the tiniest advantages is, of course, Magnus Carlsen. In an equal position, at first his opponent has many moves to keep the game equal. But as he squeezes and squeezes, the game gets longer, the time lower, and slowly the number of holding moves for his opponents starts to shrink. At first it's 7, then 5, then 3 and then suddenly there's only one move to save the game. In the best case it's a natural looking, easy-to-find move, in the worst case a practically unfindable 10 move computer combination. When you're merely looking at the engine evaluation of such a game you might think "Oh, this game is equal", "Why do they keep playing, it's an equal endgame?" and then suddenly and seemingly out of the blue: "Oh my god he blundered!!".

The takeaway: don't blindly trust engine evaluations, the practical reality often is a lot more complicated.

How to work with engines as a beginning to intermediate player

Despite all the pitfalls, engines are a powerful tool to improve your chess. However, don't beat yourself up for not finding computer lines - not even the pros always do. When analysing a game, try to understand your mistakes as good as you can, but if there's a line you simply cannot comprehend, just let it go.

Stay sane out there!