From Sega Retro
Anti-aliasing is a programming technique used in video games to make lines and images appear smooth, and not blocky or pixellated. The process involves blending areas of color, or averaging two adjacent areas of color. Anti-aliasing was first widely used in games for the Nintendo 64, although the effect was often to give the graphics a "fuzzy" appearance. Subsequent games consoles have used anti-aliasing to better effect. The PlayStation 2 console is somewhat notorious for its lack of anti-aliasing in most of its games; most people call the rendered lines without anti-aliasing "jaggies."