There is no short answer to what modes are, because it can only be understood with a good knowledge of music fundamentals - intervals, transposition, and key signatures - and some music history.
Part of the reason leaning about modes is difficult is because there is a very, very long history of modal music. There is modal music from the Medieval and Renaissance eras, folk music both old and modern, modal aspects to rock music, and modal jazz.
Most of the introductions I've seen spend little, if any time, explaining the history, and teach something along the lines of playing a scale an octave of all white keys on the piano -
C for ionian mode,
D for dorian modes, etc. - which you can also call rotations or modes of the
C major scale.
C major sort of gets close to the origin of the modes, but the history is more linked to staff notation. On staff the origin of the modes involves no key signatures and scales spanning octaves starting on pitches
D for dorian,
E for phrygian,
F for lydian, and
G for mixolydian. That isn't the complete picture, but we don't need to go into further detail. The point is to get the historic association with staff notation. You can read up on Church Modes to get the details.
Continuing the history in a very abbreviated form flats and sharps get introduced to the modal system and eventually the concept of major and minor keys emerges. Music theory sometimes calls the new system the major and minor key system.
Another way to understand modes is to sort of "reverse" the history and take (what I hope for you) is the familiar major/minor keys and understand how chromatic alterations to them produces modes. The alterations consist of lowering scale degrees by a half step in all cases but one which involves raising a scale degree by half step. Those alteration move through the various degrees of a major/minor scale by fifths, which makes things systematic, but you don't necessarily need to know that.
We can continue by bring in your first question...
All I see about these modes uses C major scale as the Ionian mode. Can other scales be Ionian? For example, can B# (edit: B# doesn't exist, I meant to type Bminor. I apologize) scale be Ionian?
B# exists. It's just enharmonically equal to
Yes, other scales can be ionian. You can have any starting pitch ionian.
Db ionian, etc. etc. This is where understand the modes as alterations of a major/minor scale comes into play. It's possible to alter a major scale six times to get all seven of the "modern" modes: ionian, dorian, phrygian, lydian, mixolydian, aeolian, and locrian. But you can also group those modes into major and minor families and make the alterations from either a major or minor scale. I prefer the later.
^ and a numeral indicate scale degrees. Ex.
^5 means the fifth scale degree. In
C major that would be the pitch
All raised and lowered scale degrees are raised or lowered by a half step, use the original pitch letter and apply accidental sharps or flats accordingly, don't use enharmonic changes to the pitch letters.
The basic major and minor scales are based on key signatures so the minor scale is the "natural" minor scale.
Major family of modes:
- Lydian = major scale with raised ^4 :C D E F# G A B C
- Ionian = major scale :C D E F G A B C
- Mixolydian = major scale with lowered ^7 :C D E F G A Bb C
Minor family of modes:
- Dorian = minor scale with raised ^6 :A B C D E F# G A
- Aeolian = minor scale :A B C D E F G A
- Phrygian = minor scale with lowered ^2 :A Bb C D E F G A
- Locrian = minor scale with lowered ^2 ^5 :A Bb C D Eb F G A
That organization is nice, because it groups the basic tonalities by the quality of the third scale degrees either major third or minor third.
All seven alteration from a major scale...
MODE MAJOR SCALE ALTERATIONS IN C PITCH LETTERS MAJOR KEY/MODE SIGNATURE
- C Lydian = major scale w/raised ^4 = C D E F# G A B C = G major/C lydian, 1 sharp
- C Ionian = major scale = C D E F G A B C = C major/C ionian, 0 sharps/flats
- C Mixolydian = major scale w/lowered ^7 = C D E F G A Bb C = F major/C mixolydian, 1 flat
- C Dorian = major scale w/lowered ^7 ^3 = C D Eb F G A Bb C = Bb major/C dorian, 2 flats
- C Aeolian = major scale w/lowered ^7 ^3 ^6 = C D Eb F G Ab Bb C = Eb major/C aeolian, 3 flats
- C Phrygian = major scale w/lowered ^7 ^3 ^6 ^2 = C Db Eb F G Ab Bb C = Ab major/C phrygian, 4 flats
- C Locrian = major scale w/lowered ^7 ^3 ^6 ^2 ^5 = C Db Eb F Gb Ab Bb C = Db major/C locrian, 5 flats
Notice how the seven alterations to major move through the scale systematically by descending perfect fifths (with an implied
^4 ^1 ^7 ^3 ^6 ^2 ^5. If you spend some time with that chart you will eventually see all the key signatures and 7 modern modes are linked together through a process of transposition and starting pitch rotations.
So, yes, you can have any of these seven modern modes on any starting pitch. Just alter the necessary scale degrees, and be aware you may need double sharps or double flats to spell things correctly...
^1 ^2 ^3 ^4 ^5 ^6 ^7 ^1
- `Gb` major = Gb Ab Bb Cb Db Eb F Gb
- `Gb` phrygian = Gb Abb Bbb Cb Db Ebb Fb Gb
For example, can B# (edit: B# doesn't exist, I meant to type Bminor. I apologize) scale be Ionian?
I'm really confused what you mean - can
B minor scale be ionian?
B minor is
B minor, there's nothing ionian about it.
If you're trying to rotate through the modes of
B minor until you get to the "ionian mode", or you could state it like this
B minor has a key signature of two sharps, what ionian mode uses two sharps?, the answer is
D ionian. Yet, another way to state it is
B minor's relative major is
D major, and
D major is the same set of pitches as
- B (natural) minor is aeolian mode: B C# D E F# G A B
- D major is B minor's relative major
...which is D ionian mode : D E F# G A B C# D
D major, and
D ionian all use the same set of pitches, but the tonic or final (the starting pitch) changes.
B ionian is a completely different set of pitches.
- B ionian is B major : B C# D# E F# G# A# B
Now for the second part of your question...
I think I understood that modes change throughout a song. Do they change with the chord progression? For example, lets take the C major progression: C-G-Am-F. Will the modes then go Ionian-Mixolydian-Aeolian-Lydian? If not, when do they usually change?
This is basically the "chord/scale" system, and you seem to understand how it wants you to think about playing over a chord progression.
I think that is a really bad system for teaching music, because it makes a jumble of concepts: tonality, chord, scale, mode, and key. That system takes major/minor key chord progressions and labels scalar segments of the key as "modes." The problem is two-fold: it conflates several harmonic concepts - chord and tonality, mode and key, and it also encourages diatonic scalar noodling.
If the song is in
C major, and you play scalar passages over chord changes
C G Am F, you're still playing in
C major. Just because you play a scalar passage in
C major that runs, for example, from
A5 down to
A4 doesn't mean that you suddenly are playing in
A minor or
A aeolian. The key/mode is not changing.
If not, when do they usually change?
It depends on what the song does. The example you gave is only
C major and progression
C G Am F. Indeed some songs do nothing more than that and it most likely wouldn't be appropriate to say that anything about key or mode is change in such a song. In fact, the hallmark of such songs is the tonality does not change.
It's possible that a song in
C major has a section that modulates, for example, to
A minor. At such a change you still aren't talking about a change of mode, you're talking about a change of key. For that section the obvious thing to do is play in
It's also possible that a song in
C major could change to a section that is actually modal. You could have it go like
C G Am A7 and then shift into a section in
D dorian, a section of actual modal music. It would then make perfect sense to describe that as starting in
C major then changing to
If you described the same thing the "chord/scale" system way, it would be - play
F lydian, next section play in
D dorian - which looks like a whole lot of modal playing rather than playing in one major key
C followed by playing in one mode
D dorian. I think the later is a much, much better description.