What kind of ID do I need to use at the airport when traveling?

The reason why I am asking is that back in 2009 I was travelling from St.John's, NL and they asked me about some ID like a picture ID at the baggage desk and when boarding the plane and again they ask me at the airport in Montreal when I was coming home to Newfoundland. They asked me if I got a driver's licence which I don't have cause I don't drive. So I am wondering what kind of ID, I should have? and where can I get a picture ID on it?