Minor scales (three different scales?)

Hello,

I wonder why there are so many differences between the different minor scales. There are:
-The harmonic minor scale
-the melodic minor scales (going up)
-the melodic minor scales going down.

Why are there so many different minor scales?

In a music in the mode "A minor" how does the composer decide if the F and G will be sharp or not as you always go up and down in a music, it is not regular like in a scale. Do the "A minor melodic mode" and "A minor harmonic mode" exist?

Thank you to those who were able to understand my question. Thank you very much to those who are able to answer.

Benoit

You should watch Andrews New Vid on Minor Scales. He also discuss why the different scales are created +

Here it is:

I have watched it and I have not understood why the 6th and 7th notes of a melodic scales are not raised when you go down.
I also think that the sixth note is raised for musical reasons, I read in a book that it is because it's hard to read intervals which are bigger than one tone.
In a music in the mode "A minor" how does the composer decide if the F and G will be sharp or not as you always go up and down in a music, it is not regular like in a scale. Do the "A minor melodic mode" and "A minor harmonic mode" exist?

Because you dont need to have them raised anymore, simple as that.
And why raise the 6th? Because they believed in the devil.

Benoit wrote:I have watched it and I have not understood why the 6th and 7th notes of a melodic scales are not raised when you go down.
I also think that the sixth note is raised for musical reasons, I read in a book that it is because it's hard to read intervals which are bigger than one tone.
In a music in the mode "A minor" how does the composer decide if the F and G will be sharp or not as you always go up and down in a music, it is not regular like in a scale. Do the "A minor melodic mode" and "A minor harmonic mode" exist?

It is as simple as Victor say it is, really And composers can use the scales as they want, if they like the sound it doesnt matter if the 6th note is raised or not No matter what the go for it is in the scale... And one more thing, even though you compose a piece in Fex: A minor, you can use all the notes, even though its not In the scale!! So all the rules can be bend and used as you want to. Its all about what you think sounds good. But one thing is Important. Always end on the note that starts the scale Then the piece sounds finished ... Then again, you can choose to dont do it aswell but then you will create an effect. If the effect you want is that people should sit and not feel that the piece wasnt completed then you can end on another note..

Oh I asked it because I will have to recognize the mode of different musics for my exams. I think that the modes are major or minor but not "melodic minor" or "harmonic minor". They are just minor, aren't they?

Yes.

Major =
Minor =