Why websites are divided in twelve collumns?

Question

Also, how can we measure that? Do we need to always use twelve?

Answer 1

Elements you decide to place on your webpage takes a certain amount of place (columns). This is a way yo organize your webpage.

Why twelve ? I guess this is an arbitrary choice, but you don't have to use them all, you just need to divide your page in the number of desired columns (6 - 6, 10 - 2, 8 - 4...)

Also, I'm unsure about this but the columns have a size depending of the device screen you are using, so the content can be responsive.

Answer 2

Thank you Kornhe, it makes so much sense now! :D