OK, I know I've said this a hundred times before, but here goes:
Your rating ("rating") is not a number! It's a position on a surface. The surface looks a lot like a normal distribution, or what is sometimes called a "bell curve". If you go up (towards the right side of the curve), in general, your rating should go up, but not necessarily! There are many variables that determine your position on the curve, and they don't always stay the same from day-to-day.
A more accurate assessment of your skill level might be rank, which would show your position on the curve relative to the other players in the population. Did you go up or down relative to everyone else? Do you feel like you're playing worse Chess now?
The bottom line: Chess.com uses the Glicko system, which has it's faults, but speaking in purely mathematical terms, it's much a much better indicator of relative strength compared to other systems, such as (pure) Elo. In comparison to USCF or FIDE ratings, keep in mind that tournament-based ratings need to assess the problems of "sandbagging" (which is a real concern) as well as rewarding high-level players for play based purely on event performance. Despite any system's shortcomings (since a player's true strength can never be known, only modeled), you will find that your rating here (Glicko) will be much more useful to you as a guide to your Chess progress.
The difference a day made
I started the day with a rating of 2394. A really hard work to get there. Especially the last 150 points.-
Today I saw in a game ,- which had already over 70 moves,- a drawoffer of my opponent. I had to accept. 48 points gone! Made a new rating of 2346. Not such a big loss!-
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So it was a tournament game and the rematch started automatically. I had several reasons for resigning the new game. One reason was the reduction of the number of my games. I resigned without making a move and after a few seconds saw with astonishment a new rating behind my nickname: 2250
First I could not believe it. Normally you resign a game at the beginning it doesn`t touch your ratings. Therefore I wrote to chess. com and asked about it- The correctness of rating loss was confirmed. Tournament games ( not others) are counted , whether you made a move or not.-
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And what can we learn from this:
Do not play for your ratings, but for having fun with your games
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Your points may go soon and unexpectingly down, but your fun with that game will not do! If fun it is your true reason for playing chess
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Edit:
Bytheway, it would be from interest for me, why there is made such a difference of rating adjustment . I cannot see any sense in it, because both goes into the same rating.
Why can I loose in a not played tournament game almost 100 points and haven`t got in other games, where my opponents resigned immidiately, no points?-