Is this considered cheating?

you can leave yourself a private note on that player after a game so you know what they play in case you get paired with them again and there's likely time for either colour to check that note next time before moving

I would disagree that what you do is before the game. It's during the game, you just haven't moved yet. And thus I would consider it cheating.

It's not considered cheating in OTB to research your opponent's opening repertoire before you sit down to play, for example as soon as the tournament pairings for the next round are posted on the wall. Is this an intrinsically different situation from when you are playing online and the game has started but the players have not made a move yet? Or at least Black has not made a move yet?

It's debatable.

@Brian-E said in #13:
> It's not considered cheating in OTB to research your opponent's opening repertoire before you sit down to play, for example as soon as the tournament pairings for the next round are posted on the wall. Is this an intrinsically different situation from when you are playing online and the game has started but the players have not made a move yet? Or at least Black has not made a move yet?
>
> It's debatable.

If you want to make a fair comparison, you would have to imagine someone sitting down behind the board of an OTB game, and only then reading chess books and openingbooks. If you're black your opponent may even make his first move while you're doing that. I'm pretty sure that will not be tolerated.

I would consider its not cheating, so long as no moves have been played.