Backstory for a character is an aspect of Tabletop RPGs that is often misrepresented as one of the weirder/dorkier elements. Though it can be very detailed, it is also a staple of the game, so much so that companies have actually created full guides or generators to help players create a cohesive story.
However, many people disagree with the necessity of the backstory. They see a detailed backstory as frivolous. Essentially, many GMs don’t care where your character is from as long as they are motivated to the adventure and stick to the campaign. That’s their prerogative, so fine, let them run the game the way they want, but I personally feel this approach to a key aspect of character creation comes from a vast misunderstanding of the importance of backstory.