Rook Promotion question

So I'm still relatively new to chess, and from my understanding, you should pretty much always want to promote to either a queen or in some rare cases a knight if it would let you fork/check in an important way. However, I've been doing a lot of puzzles and also some assisted games with the computer giving suggestions, and it seems like the computer does a lot of rook promotions for some reason. I think the main time I see this happen are when they know their piece is doomed anyway so they choose rook. Is there some special reason for this? Why not just pick queen anyway regardless of whether the piece is doomed? Is there some kind of hidden score meaning or some kind of inside chess code to it? And yes I know there are also situations where promoting to a queen could be a draw, but the situations they do them aren't those.

When these situations happen in puzzles I see the puzzle has "Underpromotion" category but that completely confuses me because that category makes me think there's actually some deeper meaning/emphasis as to WHY rook was chosen, but I just can't see it knowing the situation is where the piece is doomed to die no matter what they promote to...

Depends on the position. 

Ideally a queen is good.  But their are times when promoting to a queen, would cause stalemate. 

As long as you have enough material to mate ( Queen, or Rook) then go or the mate.  I have seen numerous posts here with people complaining they were winning, and ended up in stalemate because instead of going for the win, then get greedy and keep promoting to queens.

If you haven't already.  Learn how to mate with a queen,  and or rook. 

@Rornan215, do you have an example of such a puzzle?

If it's officially labeled "underpromotion", I'd indeed expect that promoting to a Queen leads to stalemate.

That's the thing, the situation where I saw the puzzle listed as underpromotion was in a situation where my very next turn I was going to capture that promoted rook. You should think that if it were a stalemate as queen situation that would be impossible because a stalemate would only occur if I had no moves, yet clearly no matter what he promoted to I still had the move to capture that doomed piece...

As Sred has posted.  Unless you post an example, all we can do is post general advice.

As SoupTime4 said, without an example it's just guessing, but note that on some sites the tags are assigned by users and not necessarily verified.

Edit: I assume that in the position you described, the underpromotion didn't matter and and it was tagged wrongly.

I don't know how to link any specific puzzle I solved. I don't even know how to get back to a specific one that was lost when I refresh the page, or else I'd browse through my recent puzzles to try to give an example.

@Rornan215, anyway if there was no stalemate involved and the piece was supposed to be captured anyway, there's no deeper meaning to it.

I am no computer expert, but I have the following guess:
The engine works by making a list of legal moves in a position, and then evaluating each move, then ordering them in order from best move to last move, and in the end spits out the best move according to the analysis it has done. How does it order 2 equally good moves? Probably by taking the first move from the list of legal moves. So the reason it prefers rook promotions is probably the simple reason that when it considers pawn promotions, the first listed is a rook.

When I was a kid and analysed K+P vs K, Fritz always wanted to go diagonally away from the pawn just before stalemating its opponent. I recently figured it was because it is the first in the list of legal moves.

Maybe some chess engine programmers could shet more light on this subject. 

Yeah, that was my impression from my games with the computer, since the computer is counting that piece as lost either way (for example when they promote just to simplify the game so that their other queen/rook/etc will capture their attacker), it probably values all promotion options pretty much the same, and then the algorithm probably defaults to rook.

Another thing I noticed is that the easier computer difficulties (which I'm starting with since I'm still learning), the one thing they seem programmed to do to give you an edge is that they are reluctant to retaliate against your knights/bishops, so there was one game where I was about to promote after capturing their rook with a pawn, and I purposely picked bishop thinking if I picked queen they'll definitely capture that piece (since they value me having that too high) but if I pick bishop they might not recapture it, and they didn't take the promoted bishop lol.

This is correct.

Basically, when the computer is evaluating moves, a new move must beat an existing move in order to get bumped above it.  So, if it checks e8=R first (and say the rook is going to get captured immediately) that will evaluate identically to e8=Q (which would also get captured immediately).  Since they are evaluated the same, the first one checked is the one that would be the top pick.  One of the flaws in the chess.com tactics trainer is that it does not allow for alternate moves (something programs like CT ART do allow for).

Edit:  I should also note that Lc0 tends to "troll" when it gets these situations and underpromotes when a normal queen promotion would be just fine.  I suspect that is due to the fact that a queen promotion allows more stalemate opportunities than a rook promotion (even if those opportunities are almost never forced).

I recommend not to make that a habit

Look up  Saavedra position. It's the most famous rook promotion example.

But avoiding stalemate is involved here. That's not what the OP is talking about.

Here is the Saavedra position, named after a Spanish priest who died in 1922.

There are some well known positions in which promoting to a queen will cause stalemate, and rarely, but occasionally, comes up in actual play.

Now, I have on occasion promoted to a knight in order to limit a king's escape squares, or protect a specific piece so I could just force a mate. In the case of protecting another piece, it's always because mating is quicker than promoting to a queen.

Pieces don't have actual value, only relative value. Chess has only 2 option: a player wins the game, or the game is drawn. 

I think posts 9 and 11 come closest to answering your question. Other than under promotion being required to avoid stalemate, there is no special, secret, or hidden scoring meaning or point system that values under promoting a piece that will be captured on the very next move. It's not like the computer "says" oh, if I promote to a Queen and get captured I lose 9 points, so I'll promote to a Rook and lose only 5.

If, however, you are doing an under promotion puzzle, then by definition the pawn will be promoted to a piece lesser than a Queen. And almost always the reason is that under promoted piece (such as a Knight) is required for a tactical reason, either to checkmate the opponent or, as mentioned above, to avoid stalemate. In these instances, take a moment to see how having a Queen on that square would change the outcome.

In rare practical situations, promotion to a bishop or a knight can even be useful. I once played with one of my friends online who promoted a pawn to a bishop on a1. I had a rook along the a-file and a king along the first rank.

Of course I captured it, but there were implications if I mouse-slipped. Promoting to a queen would be check, so there was a very slim chance I can mouse-slip online (if I moved my rook and it landed one square away from the checking queen, I could still get another shot since the site prohibited illegal moves from being played). So my friend was clever to promote the pawn to a bishop. If my rook really landed on a2, it would be considered a legal move, and the bishop can escape.

Sometimes under-promotions are played because of this.