Modes are types of scales that date back to Ancient Greek times, making them much older than our very familiar major and minor scales, which date back to about 1690 when they were regularly used as a basis for many musical compositions.
There are 7 modes in particular that are still used and they are:
Ionian mode – this mode is usually described as using the notes C, D, E, F, G, A, B and C. This means that the Ionian mode is exactly the same as a major scale in structure, with a pattern of; tone, tone, semitone, tone, tone, tone, semitone.
Dorian mode – this mode is usually described as using the notes D, E, F, G, A, B, C and D. This does not mean that it is like C major scale and it certainly sounds different when you play it in order from D up to a higher D. The Dorian mode has the pattern of tone, semitone, tone, tone, tone, semitone, tone.
Phrygian mode – this mode can be described as using the notes E, F, G, A, B, C, D and E. Again, even though it might look like its C major jumbled up, it actually sounds quite different to the other modes. The pattern of tones and semitones is; semitone, tone, tone, tone, semitone, tone, tone.
Lydian mode – this mode is often described as using the notes of F, G, A, B, C, D, E and F. This mode sounds a bit like a major scale but with a wonky 4th note (at least this is the way it sounds to me!). The pattern of tones and semitones is; tone, tone, tone, semitone, tone, tone, tone.
Mixolydian mode – it is no coincidence that the mixolydian mode has the word ‘lydian’ name within it because it is considered related to the Lydian mode. The Mixolydian mode is often described as using the notes of G, A, B, C, D, E, F and G. This mode also sounds somewhat like a major scale, except the seventh note ‘F’ sounds off and you can see that most of the notes (except for the F) is found in the scale of G major. The pattern of the notes goes: tone, tone, semitone, tone, tone, semitone.
Aeolian mode – this mode is frequently described as using the notes A, B, C, D, E, F, G and A. It is the Aeolian mode that is actually the same as the natural minor scale and it follows the pattern of tone, semitone, tone, tone, semitone, tone, tone.
Locrian mode – this mode is often described as using the notes of B, C, D, E, F, G, A and B. This particular mode has the pattern of semitone, tone, tone, semitone, tone, tone, tone.
It is important to note, that each of the modes can be transposed to have different starting notes, but the pattern of tones and semitones, which make each mode distinctly different, must stay exactly the same.
So these are known as the 7 modes and even though they are not that commonly used in classical music, they are certainly used in advanced jazz music. It is rare for them to be used in popular music.
If you are still trying to get your head around major and minor scales, I suggest that you wait to really learn about modes until you have a thorough understanding of major and minor scales and how they can be used.