The major scale is the mother of all music scales. The majority of popular and western music is based on the major scale, from classic to heavy-metal. Songs by Guns N’ Roses, Metallica, The Eagles, Led Zeppelin, The Beatles, Pink Floyd are primarily based on pentatonic and major scale patterns.
So if you want to become a good guitar player you have to know them well.
Here are the fingerings of major scales in all 12 keys.