Blues is where rock guitar started. Artists like Chuck Berry, The Beatles and The Rolling Stones were heavily influenced by this genre.
This 12 bar pattern (so called because there is a set of 12 bars that rotate) is essential knowledge for all guitarists.
Once you know this pattern you’ll be in a better position to “jam” or improvise with other guitarists.
TOP TIP – Keep your index finger held down on the second fret whilst playing the fourth fret with your ring finger.