There are plenty of online resources that go into great detail when explaining music theory. However, I find that most of these resources are overly complex and packed full of unnecessary jargon. My goal with this article is to use plain English to describe the basic music theory that every guitarist needs to know.
Modes are scales that allow you to improvise over different types of chords. They are particularly useful to improvise over chord progressions that include chromatic chords (i.e. chords that do not belong to the key of the progression). You create a set of modes by starting a scale on a note other than the root and then continue to ascend for an octave.
Learning different scales, such as the minor pentatonic scales, can be a really quick way to learn your way around the fretboard. By practicing scales, your fingers will become more fluent with chord changes as well as location of each note which is vital to learning new specific songs and riffs.