This article is from an Australian website and is referring to travel in Europe.
I added it because I know numerous budget airlines in Europe (like RyanAir) have a lot of little known rules that end up costing their travelers a lot of money. One rule is the RyanAir visa stamp that only RyanAir requires. Non-EU members (ie. Americans and Canadians) have to check in at the RyanAir desk and then go to a different RyanAir desk to get the RyanAir visa stamp. But RyanAir will never tell you this. You have to go through security, sometimes take another bus out to the plane. Right before you board they'll tell you you can't board the plane because you don't have the visa stamp that only they require. By that time it's too late to go all the way back to get the stamp.