Can someone explain the game summary to me?

Hello, I don't understand the post-game summary(mistakes,blunders,missed wins). I would like to know how these are generated. The summary of one of my games is 0,0,0,  but the analysis contains 1 missed win. Is it an engine report at a low depth? Also, sometimes when you reload the page, the numbers change. Why is that? Thank you.

A mistake is a move that has either long-range tactical effects, like a poorly-played knight move, or a play that gives away a piece like a pawn for free. A blunder is when you accidentally do something foolish in the game, like give away your queen or hang a free checkmate right in front of your opponent. A missed win is usually a play, that, if done properly, forces checkmate with best play. And, if your summary says 0, 0, 0, but there is a missed win inside, perhaps it's just a small bug because it's never happened to me. I also don't know about the numbers changing issue. Perhaps it's just something with how Chess.com works.

A mistake (?) is a move that turns a draw into a loss.
A missed win (?) is a move that turns a win back to a draw.
A blunder (??) is a move that turns a win into a loss.
The engine does not have it right all the time.
At higher depth e.g. after reloading the verdicts may change.

I know what the numbers mean, but thank you for the explanations. As for the numbers changing on reload, I'm not sure the repeated analysis is more accurate. Try going to my profile and open the game with YaBoiJeremy. This is what I get between reloads:

Another reload shows 3 blunders.

Have you tried reloading the page? Does the number of blunders change?

By itself, it's junk and a waste of your time. Use a stand alone engine on your device.

As a blunder checker, it's not great. But you can run a few times, focus on earliest blunders.

Alright. Thank you all for your time.

Yall don't get it.

When you relaod, the nuimber of blunders it says changes.

Happens to me too. 

I think that changing screen is showing us white's blunders, because it shows me 5 blunders. But Black had 2 blunders and a missed win. So maybe at some point the engine decided that the 3rd "blunder" was a missed win instead, and the numbers changed for you? I dunno for sure, but I screenshot the 2 blunders and the missed win above

The engine couldn't have changed it's mind because my screenshots show 1,2,0 and 1,3,0. If it decided that a blunder is a missed win or a mistake the numbers would be different.

What if it changed it's mind about more than 1 move?

Yeah, well I agree with what you are saying. I don't know the answer to your question. Those generalized numbers aren't much useful anyway, did you run analysis on the game? In case you are a free user, I have attached that game analysis below in case it may help you:

Thank you for the annotated analysis. I'm a free user, so I can't get a computer analysis of every game without resorting to external tools, so I use the summary as a general indicator of my play. At least now I know it isn't 100% correct.

Take my notes with a grain of salt: I am not a good player. I just commented based on the engine analysis and the lines the engine was preferring in the game, because I didn't know if you would be able to click the "Go to Analysis" button and see the actual analysis.

I thought you did pretty good, personally. And you are welcome

https://www.chess.com/forum/view/game-analysis/why-is-this-position-1-for-white

Might be some help

The summary and specifically "accuracy" is called chess.com "CAPS" (Computer Aggregated Percentage Score). How computers calculate this is an interesting discussion that can be an article in itself and various chess engines calculate this slightly differently. The short version of what happens is basically the computer calculates a bunch and then assigns an evaluation at the end of the long line(s). The computer then chooses to play the move the results in the line with the evaluation most in their favor (as far as the computer can currently calculate). 

It calls their choice the "best move" and then evaluates the other moves and lines as worse by however many "centipawns" it judges. A centipawn is a unit the computer uses to judge chess positions; one centipawn is worth 1/100 of a single pawn. Evaluations that are positive favor White and negative favors Black. An evaluation of (+0.29) is favoring White by 29 hundredths of one pawn. An evaluation of (-0.78) favors Black by 78 hundredths of one pawn and so on.

If your chosen move is a certain amount "worse" than the "best move" then it declares such move a "blunder." Similarly, "mistakes" are smaller blunders and "inaccuracies" are even smaller than mistakes.

The reason why the numbers (evaluation) sometimes changes even upon reloading the page is because the computer might calculate slightly longer one time versus another, so it changes the end-results. Running a deeper analysis (letting the computer calculate longer) will give a generally more reliable evaluation that is less likely to change as much. Even still a few rare positions chess computers still don't understand as well as human grandmasters, but that too could be a deeper conversation. 

Here is something that may be useful; it is IM @DanielRensch talking about CAPS.

Nice response!