MSAA
Anti-aliasing that takes several depth and coverage samples per pixel but runs the pixel shader only once, so only geometry edges get smoothed.
MSAA (multisample anti-aliasing) became widely available in graphics hardware around the turn of the millennium as a cheaper alternative to supersampling. Rather than shade every subsample, rasterisation is evaluated at several points per pixel while the fragment shader runs once and is shared across the samples that are covered. The coverage and depth values are then resolved into a single colour.
The payoff is smooth polygon edges without multiplying shader cost. The price is the bandwidth and memory for the widened framebuffer, and the fact that it does nothing about aliasing inside a surface — shimmering specular highlights and alpha-tested edges are left untouched. That is where post-process methods like FXAA take over.