Overdrive

Overdrive is the mildest of the three distortion types and, to many, the most musical. It imitates what a tube amp does when pushed: a soft, dynamic saturation that responds to your pick attack. Played softer, the tone stays nearly clean; hit harder, it breaks up.

Character — Warm, compressed, transparent. An overdrive doesn't "destroy" the guitar's base tone but thickens it. Many use it to push an already slightly driven amp further (stacking) rather than taking all the distortion from the pedal.

Two philosophies — Transparent: colors little, lets the amp character through, adds only saturation and some level. Midrange-focused (Tube Screamer style): boosts the mids and trims the bass — pushing the guitar forward in a band, a very common, recognizable sound.

Prominent references — The Ibanez Tube Screamer (TS808/TS9) is the epitome of the midrange-focused overdrive and probably the most copied effect of all — "Tube Screamer style" has itself become a tonal term. For the more transparent direction, tonal touchstones like the Klon Centaur (and its countless "Klon" clones) or the Boss BD-2 Blues Driver. These names serve as reference points, not buying advice.

Typical controls — Drive/Gain (amount of breakup), Tone (treble amount), Level/Volume (output). The level control also makes the overdrive a solo boost.

Overdrive is the first drive pedal many start with, because it comes closest to the natural amp sound and works with the amp rather than against it. Whether transparent or midrange-focused fits better depends solely on the desired tone — both are valid paths.