a gap year, especially common in much of western europe, is a year in between the end of childhood education(say US high school) and the beginning of adult education(say US university) where a young adult is encouraged to find themselves before choosing their exact field of interest or life path.

It is common in many countries.

That is a type of gap year yeah. The stereotypical one is obviously that of which someone goes on holiday for most of a year without any responsibilities but it's harder to do that when you don't have the money to support it.

Over here its very common to do your studies but you take an additional full year after the end just for your thesis. During the year people usually work, travel and do the thesis.

Not a thing in most of Asia that I know of, but it should be, I could have used a break from the rat race for a bit when I was younger and maybe put some real thought on what I want to do with my life

it is for college, some people take 1year off from school and then come back, usually changing thier majors, or even going to a different field. you dont want to be graduating with a degree you dont like, since you wont get financial assistance after you already graduated.

if you mean a gap year "from a job, like quitting it" that is abnormal, and usually indicates something deeper going on.