Only options are "Check" or "Raise"?

Under what conditions do I get the options to either "Check", "Raise" or "Fold" (no Calling)?

A trick question?

If not, check is when you are the big blind and there were no raises. You already have put the same amount into the pot as everyone else who is playing, so you are not "calling" anyone's bet, you led the betting with the big blind so everyone else had to call your bet. So, check says you want to play as is, without raising everyone.

No, it isn't a trick question. I encountered a turn where the only buttons available for me to click were "Check", "Raise" and "Fold".

I should mention that I was the Big Blind at the time.

It means there were no raises before you. You can't call a raise if there is no raise.

So, is that all clear for you? I mean, I'm no expert, but we were all raw beginners at some time.

The only time this happens is 1) you are the big blind, 2) it is in the preflop betting stage, 3) someone called your big blind, 4) no one raised.

At this point there is no bet for you, as the big blind, to call because you put in your money before the cards were delt, so you cannot call your own bet. Someone else called your big blind bet, but, as the big blind before the flop, you have the option to still raise their calls.

As Mr.Bove says, if someone raised, then you would have the option to call their raise.

It can occur any time post flop if there has been no bets to you.

Pre flop you have to be BB with no raises to you.

Thanks for the explanation fellas. I think I understand, but it's just a little big vague. Is there a website available for me to read up on it more?