Ever since the early days of the electric guitar players have been adding effects to change their sound. This page hopes to give a brief overview of effects without getting into wiring diagrams. The effects are listed roughly in the order they were introduced.
Where would Hank Marvin of The Shadows be without a little black box that meant his twangs went on forever. Inside the box was a loop of tape and a head that added the sound, a series of erase heads gradually removed sound creating an echo effect. Echo is now part of a spectrum of delay and reverb and usually achieved digitally but rock'n'roll players still hanker for the crude echo of tape and spring echo.
If you put a guitar amp in a room with good acoustics it sounds better. If you put amp and guitar in an anacoustic (baffled) booth at a recording studio it will sound dry and lifeless. Reverb adds in an electronic 'room echo' that sounds warm and alive. Of course if you are already in a hall then adding reverb is too much and the sound goes boomy. Reverb is now part of a spectrum of echo/delay and environment modelling digital effects but is still found on many amps. Judicious use can improve anyone's tone.
Literally this makes your one guitar sound like many. Chorus works by delaying your guitar sound and adding it back in with itself. Abbey Road studios may have been the first to create it under the name ADT or 'automatic double tracking'. Chorus is also an effect that acoustic players with piezo pickups can advantageously add to get a bigger, sweeter sound.
Take two hi-fis, put the same record in each and start them almost at the same time. The two recordings will make a washing, 'phased' sound typical of sixties psychedelic records eg. Rainbow Chaser by the 60s Nirvana. Actually this effect first occurred in the 50s on a ballad called the 'Big Hurt' but the Beatles used it alot at Abbey Road. George Martin and his engineers created duplicate recordings on two seperate tape decks and slowed down the tape reel by holding the outer flange. This account for an alternative name for this effect 'flanger'.
Ever heard the trumpet sound on the theme tune to Goldfinger? Trumpet players call it a plunger-mute because they literally stick a rubber toilet plunger over the wide end of their instrument to make a 'wah-wawaaah' sound. Wah or wah-wah pedals do this for guitarists electronically. Work the pedal and you can make the guitar yawn. Wah is a huge part of the Jimi Hendrix sound. Stuck-wah is a sweet-spot players find where their guitar sounds tight and immediate, the pedal is stuck in this position and not altered. Clyde McCoy wah pedals owe their name to a brass player famous for his plunger-mute.
Tremolo is a form of vibrato. Many guitars have a tremolo arm that allows the player to vibrato whenever it is raised and lowered which simply flexes the guitar strings. The electronic effect is more of a quavering tone and was common on sixties amps. You can hear tremolo on the haunting intro to the Rolling Stones' track 'Gimme Shelter'.
From the early days of amplifiers and electric guitars musicians started incorporating the distorted sound achieved when tubes were at high volumes. Of course, once you turned down, the effect went away. So pedals were created that created distortion reliably. Early distortion was referred to as fuzz. Fuzz guitar dominated the sound of sixties garage-punk acts.
Amp manufacturers then began to build gain controls into their amps and pedal makers have created a huge range of devices to dirty your sound up. What varies is the amount of distortion or 'clipping'. Soft clipping takes the top of the waveform and roughens it up. Hard clipping flattens the waveform entirely, producing a 'crushed up' sound.
There are various words used for distortion. While these are the same concept, they are associated with different sounds.
Ibanez Tube Screamer
This is just another distortion pedal but one with a whole cult following of it's own.
In the mid-eighties these unprepossessing mint-green Ibanez boxes came out and just became part of the scenery. Stevie Ray Vaughn used one, Carlos Santana used one, Ibanez made a few models then discontinued them.
Sometime after Stevie Ray Vaughn's death though tube screamers started changing hands for high prices. The advent of eBay made them more desirable and even a reissue could not kill the clamor for the originals. Don't expect reason from tubescreamer disciples, it's a 'if you ain't played one you don't understand' thing.