Watch the Adding the Major 3rd online guitar lesson by Fareed Haque from Jazz Rock Workshop
Using the m3 and Maj3 together is the most essential element that separates the blues and jazz from other western music. This major/minor sound creates a Dom7#9 since the #9 is the same as the m3 [ G7#9 is G,B,D,F,A# or Bb]. The 7#9 chord is at once a stable and unstable sound, it feels like a minor chord and major chord and a dominant chord. The dominant sound give the blues a feeling of wanting to move or resolve, the minor major aspect makes the blues feel like it already home. This also contributes to the feeling discussed earlier that the blues is moving, and staying put all at the same time.