Whether you want to sound like you're playing the Albert Hall, or you're after some 60s surf sounds, reverb helps you capture a real sense of space...
What exactly is reverb?
Reverb (shorthand for reverberation) is the sound of the environment you are in: the sound in a tiled bathroom will be different from that of the Albert Hall.
It is created by sound waves bouncing off surfaces and all those reflections coming together to make a dense overall sound rather than distinct echoes.
How this relates to guitar is that the sound coming from a guitar can be enhanced by some artificially created reverb to give it a sense of space, or make it more epic-sounding as notes linger in the air.
The first reverb for guitar was provided by spring reverb, an electro-mechanical device that uses the vibrations of several springs suspended in a metal tray (the reverb tank or pan).
With digital technology now allowing different types of real space to be simulated, digital reverb pedals are today's norm... although just about all of them offer simulation of the still-popular spring reverb sound.
How does reverb differ from delay?
While both delay and reverb pedals can do a similar job for your sound, the difference is that you can hear the individual repeats with a delay and set the time between them.
However, with really short delay times you can dial in a sound where you won't be ableto discern the individual repeats and get a metallic reverb-y sound, sometimes called bathtub reverb.
What's so special about spring reverb?
Spring reverb has been associated with the electric guitar ever since Fender brought out a standalone spring reverb unit in 1961.
Starting with the Vibroverb in 1963, the company incorporated reverb into their amps, where it's been ever since. That original unit has become indelibly associated with the reverb-drenched sound of surf music, but spring reverb can be subtle, too.
There's something about the way a guitar interacts with a spring that differs from the sound of a specific space: there's a certain shimmer and twang.
What are the other types of reverb used in pedals?
Some are self-explanatory as they replicate sound in a particular size of space: room or hall, for example.
Plate reverb is the type of reverb you get from an electro-mechanical device first seen in 1957 which has become a staple of many studio recordings, while chamber, similarly, is a studio reverb based on sound generated in a tiled space (a chamber).
Reverse reverb puts the envelope back-to-front, and you'll also find reverb combined with modulation or pitch-shifting.