The E7 (E dominant 7) chord carries the notes E, G #, B, and D. It is produced through taking the root (1), three, 5, and b7 of the E Major scale. It is basically an E chord, with a brought flat 7.
The E7 chord is quite an iconic guitar chord. Played as an open chord (first form) or as a bar chord, it's far used prolifically through guitarists. The lowest string at the <a href="https://instroreview.com/how-to-easily-play-the-e7-guitar-chord/">guitar</a> is an E string, so many E chords (such as E7) sense like a kind of ‘domestic’ chord on the guitar.
E7 is short for E dominant 7. The dominant 7 <a href="https://instroreview.com/how-to-easily-play-the-e7-guitar-chord/">chord</a> is a great chord, as it plays a very important function in any given key.