Is There An Unwritten Rule Against Using A Database

This seems like a bit of gray area to me, since databases of computer games are coming into use.

I think these are also allowed, although I never used one. I don't think it's much of an advantage usually. In most cases a good book on the respective opening is much more helpful than a db, except for very strong players.

The problem is that the database use in inherited from older ages, when "the one with the largest library wins". In those times without computers, databases (ie chess books) were allowed because well, how to enforce their banning? Plus it makes for interesting games too. And each serious correspondance game was finding an improvement over previous games.

Of course nowadays that silicium slaves can win the game by themselves the problem has changed. If ever the computers become brutal enough to force a draw/win against the best centaur players, this will be most likely the end of correspondance chess.

You miss the logic of the database if you think that you can simply play the moves with the highest percentages. You have to understand why to move a particular way. All the databases in the world won't tell you that.

The database does tell you what moves are most popular, and will show you candidate moves you didn't consider. That's useful information to help you to improve.

There are no shortcuts--it's up to you to analyze the positions and decide what you think is best.

Playing the moves with the highest percentages can lead to trouble if there has been a single innovation that caused everyone to stop playing a line.

it is only forbidden in live chess and otb.  in online chess games it allowed.

live chess and otb the same rules applies. it is your chess knowledge and memory pure.

if it is grandmaster games we don't understand the logic behind the moves.

GM Lars Bo Hansen said in a book" how chess games are won and lost "that some opening should only be played if you are above 2500, e.g. some opening where you play knight a3 on move 3. I don't have the book anymore the book was too advanced for me.

Sred,  Thank you so much for your beautiful and crystal clear answer to my question!  You are awesome!  :)  Jason

I think better chess players will make better use of databases if both sides are allowed to use one, so I reckon it's a question of choice between players before hand.

If I'm beaten by someone who understands how to use a database good luck to my opponent.

How enforceable is a no database rule in online chess?

It is a bit of a bore playing 20 moves of book lines. Takes away a lot of opening knowledge. Have had loads of game where the opponent loses the game 1 or 2 moves past the deviation though.

Was quite confidence boosting to find I was still in book after 15 moves in my current game, without a database in a line I didn't know.

Two questions...  Is it legal or even ethical (in correspondence chess)to look up (during the game) in an endgame book the moves to capture a lone king with a bishop, knight and king?

And, for the benefit of the unenlightened, what is a "tablebase" as opposed to a 'database'  ?    Thanks!

Endgame books are a bit of a grey area. Myself and a lot of the other players who commented think they should be ok (including the masters who commented) but staff didn't really clear it up.

As far as I'm concerned it's in the spirit of correspondence chess but I can't remember a time I've thought that I'd need one.

A table base gives you the moves to win or draw for a specific position (search nalimov tablebase). A database is just a record of previous games.

Tablebases are not allowed here at chess.com, however

Then don't play correspondence.

Too many people don't use their brain when using a database.

Correspondence chess is all about research. That´s exactly the point of correspondence chess.

If you are "not aware of such rule everyone else seam to know" then you should try reading them. Your ignorance of the rules does not give you a moral highground to decide that databases of games should not be used.