Ck raise on flop and turn?

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I'm surprised this hasn't been really explained yet, so here it goes.

We need to bet mainly for value. We shouldn't check-raise because
1) We're not protecting against anything. It's impossible to protect against a flush draw, forget about it.
2) With no PF action and passive villains, the chance of it getting checked through is way too high. Getting it checked through really sucks.

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It is possible to protect against an outside flush draw with a check raise though right ? which is why its a decent play if there's 2 suited on the flop.

Not saying its correct in this case though.

What is the criteria for check raising a flop ? obviously there needs to be a preflop raiser in a later position than yourself. But what else ? i.e is it more used to trap opponents and increase the pot when you have a good drawing hand, or when you have TPTK and want to force out opponents ??

thanks.