Effects are usually based on some facet of the human ears abilities to figure out from amplitude and frequency content variations what a sound source is doing. This was critical when the sound source might be a saber toothed tiger and early man knew when to run. Now it is a means for us to express ourselves musically by directly invoking emotion.
AMPLITUDE BASED EFFECTS
based on the instantaneous loudness of the signal, how it changes, and how quickly it changes.
-Asymmetric comp/peak compr.
WAVEFORM DISTORTION EFFECTS
All the generic ways to distort the waveform that comes from the guitar.
-Symmetrical clipping - example Ibanez Tube Screamer
-Asymmetrical clipping - example Boss SD-1
-Half wave rectification
-Full wave rectification
-Arbitrary waveform generation
FILTER/FREQUENCY RESPONSE EFFECTS
TIME DELAY EFFECTS
OTHER MISCELLANEOUS EFFECTS
-Phase lock tracking
-Voice tracking (vocoder)
-Ring modulation (DSBSC generation)