Soft shadows
Shadows with soft, blurred edges instead of razor-sharp ones — an imitation of the penumbra a real light with area produces.
A point light mathematically produces sharp shadow edges, but real lights have an area, so the edge has a gradual transition (penumbra) between full light and full shadow. Games imitate this by sampling the shadow map at several points and smoothing the result — percentage closer filtering (PCF) has been the standard trick since the 1980s — or by letting the blur width grow with distance (PCSS).
Hard shadows instantly give away that a scene is rendered; soft edges are one of the cheapest routes to believability. The cost is more samples per pixel, a trade-off against screen resolution and light count.