They're only called "Mason Jars" because that was the name of the most popular company that made them here, in the U.S. They are probably called something else, in other places, around the world. I know that they are also called "Canning Jars". I still see them at the Super Market, but I live in a "semi-rural" area. They're just heavy-duty, wide mouthed, jars with a special two-pieced lid with a rubber seal. Any good glass jar should work just as well - I use Vlasic pickle jars myself!
They are the jars your Grandmother (or Great-Grandmother) used to use to preserve fruits and vegetables, jams and jellies, etc. The process was called "canning", even though it used jars (go and figure!).