Just HOW important is castling?


It is always good to consider the situation where you can move 2 pieces in one move. I think castling is always good except in situations where the queens come of the board early in the game. Then the King can start to play an active role in the game and dont need to hide safe in the corner.

also, if your opponent also hasnt castled you may have some time to delay castling
but if your opponent has castled and is lining up rooks onto your king (even in a closed position) beware because a couple of pawn captures can result in nasty discoveries
i have been burned plenty of times by castling too early and not at all so it comes down to experience in positions
my coach has explained that one of the significant marks of improvement is to be able to deviate from “general principles” when the current position on the board demands it

DeirdreSkye (post #4) is spot on about "evaluat[ing] the position" for yourself and that with all chess principles there are "exceptions."
Castling primarily gets your King into safety, as castling usually gets the King behind a solid wall of pawns (to prevent harassment from checks) - and usually the King left in the center of the board (opening and middlegame) becomes under attack.
Additionally, Rook endgames are common because typically these clumsy pieces get stuck in the corners and develop last (estimated that 1/6th of all endgames are some form of Rook endgames); however, castling also activates (or at least makes it easier to activate) one Rook from the corner.
Chess always has pros and cons to any decision. GMs that don't castle early (or at all) have calculated that the King is relatively safe where it is and can either get away with an attack on the opponent's King instead, or because there are not enough of the opponent's pieces left on the board to truly threaten checkmate (usually at least Queens and Rooks off of the board). When a beginner does not castle, it is usually because they were distracted with something else (like a premature attack), but a strong chess player not castling should at least be a red flag to both players that they are up to something - not simply distracted from castling.
Lastly, it comes down to simply understanding the position itself. The endgame often has the Kings coming into play (as the King is an attacking piece too), but they can't do this early on due to checkmate threats from many opponent pieces (and strong ones like Queens especially). Knowing when you can "get away with" activating the King or not castling is a sign of a stronger player - but there is no "rule" that precisely tells when to activate the King or when to shelter it.
If you do not know these subtleties, then you should probably castle earlier than later. Beginners tend to neglect castling more often then castling being a mistake, so "castling early" is often told to beginners as an "opening principle" like "develop your pieces" or "control the center" - but with all of these there are exceptions, but at least they are generally true.
The question is if you're not castling, what are you spending your time doing? Castling completes development by connecting the rooks and bringing the king to safety. You need a real reason not to do it, and as stated in other comments here, sometimes there are such reasons. However, the answer to your question is 'very'.


Castle when you want, not when you can. That being said, castling isn't necessary unless the position dictates that it is.

In classical openings GMs are probably castling in >99% of games (1.e4 e5 and 1.d4 d5)
In all other openings it will still be much >50%
You can delay (or omit) castling when the center can't easily be opened.

When you learn chess this is one of the prime things a lot of people teach, whether it's videos or books. But how important really is castling? I notice when I watch some people play chess on Twitch that they don't always castle, some of these people are Grand Masters. Now, is this because these people are that advanced, that castling isn't on their priority list?
I do notice that when I can't or don't castle for whatever reason, that I tend to be more on the defensive and games are more difficult, but then on the other hand I've played lots of games where I've castled and still lost out.
Castling enables your king to flee onto a flank while simultaneously developing a room. In the older items of chess, castling was so valuable a player was charged with two moves instead of one.


https://www.chess.com/live/game/3162565325
Check out that game on why you should consider castling first.
When you learn chess this is one of the prime things a lot of people teach, whether it's videos or books. But how important really is castling? I notice when I watch some people play chess on Twitch that they don't always castle, some of these people are Grand Masters. Now, is this because these people are that advanced, that castling isn't on their priority list?
I do notice that when I can't or don't castle for whatever reason, that I tend to be more on the defensive and games are more difficult, but then on the other hand I've played lots of games where I've castled and still lost out.