Some designs also offer other facilities including audio compression, de-essing, noise-gating and limiting.
A high pass filter button is present in many cases, as well as semi or fully parametric equalization.
Depending on the design of the mixer, there may also be knobs for auxiliary sends, typically used for monitors and effects units.
Depressing this button can display the level on a signal meter, and will also route the audio of that channel to a headphone output.
On a digital mixing console, the process is usually the same, but often many of the adjustments are consolidated into a common set of knobs.