Game Resolution in unity ?

I would like to know in what resolution should i have to start creating games in unity ???i just made a background for a 2d game to check how it looks,while running the scene i found only half of my background in view .and it was very boring to see that. so anyone there,please help what might be the resolution i should use while designing a 2d game background??? And how about a 3d game in the sense?

Its whatever you want it to be and whatever you set it to. If you want to only see your background image, set the screen to the same size as the image, or enlarge the image to the size of the screen etc.

One way to change the screen size is using ‘Screen.SetResolution’. Reference to Screen class HERE.