It's LCC = Low Cost Carrier (it's higher up the thread).
Try a search on something like "budget airlines" and the route you're interested in. Otherwise you just have to know what they are, eg. Air Asia is a brilliant LCC for travelling to and around Asia.
Finding LCCs is a little difficult since they are not usually listed on flight finder websites as noted above. If you start a new thread on the appropriate branch/es and ask what LCCs exist to service the route you want to fly, then those in the know will no doubt give you some names.
For example, to fly from Canada to the UK, there used to be several but now there is really only one and that is Air Transat. But they sell tickets directly or through A company called Canadian Affair. On any given day one or the other might have a lower price.
Sunwing besides being a tour company also has their own airline and can have some cheap offers to Europe as well. But I don't think they fly year round to Europe.
I know this is an older thread, but I had a bad experience booking with Kayak. Thankfully, it was only for a few days' stay at a hotel. I enjoyed using their search engine, but their booking services are horrible. If you have any problems with your reservation, all calls go to India and the agents work off a script. You will go through the same script every time you call and getting a refund is next to impossible. I used other booking sites and I never, ever had thins kind of problem. I eventually had to dispute the charge on my credit card and got my money back.
I would differentiate between their search services and booking through them. Use their search engine for research, but book through another site or directly.
DO NOT PURCHASE FLIGHTS THROUGH KAYAK I booked flights through Kayak for my family and me for a trip this June to the World Cup. Booking the tickets was easy enough after being redirected to Travelocity. Everything was very simple until I received an email stating that my flight itinerary has changed and to call the Customer Support Center to confirm the changes. It took me five phone calls each lasting over 30 minutes to fix my flight itinerary. The first four times I was told by "Dennis", "Katie", "Ricky", and some other made up name for their overseas support person that they could not get through to the airline to fix my flight. Finally, on the fifth try, I was able to arrange my return flights so that they worked for my travel dates. Great! Done! Now I can get on with my life!! Except, when I get the confirmation email the next day listing my new flight itinerary, I notice that they also changed a flight on the last leg of my outgoing trip so that I am now missing a connector flight to my final destination. This was never reviewed with me during my five phone calls so I have no idea why they changed it to begin with. Now I am in the process of getting this flight fixed. I'm two calls in. The first time, I got the same response, "We're having a hard time connecting to the airline. Please call back." This morning, I just got off a call with "Nancy" where I was on hold for over 30 minutes before my call was picked up. When I explained to her the situation, she said that I'd need to contact the airline directly. What?!! I was very adamant that I would not be doing that since this was their mistake and that they need to own it until it's resolved. After a few minutes of back and forth, "Nancy" finally realized that it is indeed an issue that they need to fix. So, she calls the airline and guess what? She's having a problem connecting and I'm asked to please call back in a couple days. Unbelievable!!!!!!!!!!! NEVER EVER WILL I BOOK THROUGH KAYAK AGAIN!!!!!!!!!!!!!!!
