EQ
Equalisation; an audio tool that boosts or cuts specific frequency ranges to shape tone.
In Depth
EQ is the most fundamental tone-shaping tool in audio production. Graphic equalisers divide the spectrum into fixed bands. Parametric equalisers allow precise control over frequency, gain, and bandwidth. EQ is used at every stage: instrumentalists shape their tone with amp EQ, engineers sculpt individual tracks during mixing, and mastering engineers make final tonal adjustments. Subtractive EQ (cutting problem frequencies) is generally preferred over additive boosting.
The smiley face EQ curve (boosted bass and treble, scooped mids) became so popular on home stereos that it has its own preset on most consumer audio equipment.