Sampling
EEVEE uses a process called Temporal Anti-Aliasing (TAA) which reduces Aliasing. TAA is sample based so the more samples the more aliasing is reduced at the cost of performance.
Reference
Panel:
Render ‣ Sampling
Viewport
Samples
The number of samples to use in the 3D Viewport. When setting this to zero the viewport will be resampled continuously.
Temporal Reprojection
Reduces noise while moving the viewport or during animation playback. Can leave some ghosting.
Jittered Shadows
Enable jittered shadows on the viewport. Jittered shadows are always enabled for final renders. This also affects shadows casted by transparent shadows.
Render
Samples
The number of samples to use in the final render.
Shadows
Rays
Number of rays to trace for each light. Higher values reduces the noise caused by random shadow sampling.
Steps
Number of shadow map sample per shadow ray. Higher step count results in softer shadows but have a higher cost.
Volumetric Shadows
Approximate light absorption of the surrounding volume objects. This makes the volumes more opaque to light. This is a very computationally expensive option and has limitations.
Steps
Number of steps to compute volumetric shadowing.
See also
Resolution
Resolution percentage of shadow maps.
Advanced
Light Threshold
Minimum light intensity for a light to contribute to the lighting. Used to compute the distance at which to cut-off lights influence. Lower values improve performance.
See also
Custom Distance overrides this setting.