How do I know what key to write in?

Question

I've recently become obsessed with **Les Miserables** and **Miss Saigon**. The music has inspired me tenfold to compose, write similar music.I've posted on here before on how to compose, and I'm trying my best but struggling with something: **When you denote the time signature, you also have to say what key it is in, right? For example: A Minor etc... but how do you know what key it is in exactly? It is the first note you play; does that become the key it is in?** I know what I want it to sound like. I have a vision in my head, but I wouldn't (at this stage) know what 'key' it is in. I am a beginner, but very determined and would appreciate some help.

Answer 1

Congratulations on your determination! I love those two scores myself—I played keyboard in their pit orchestras on Broadway—and I encourage you to keep going!

The key signature actually comes before the time signature, and the key signature gets repeated on every line of music (unlike the time signature, which is only at the beginning, or when it changes).

The key signature tells you what scale is used to make (most of) the notes of the song, and which of the notes of that scale is the "tonic" or home note. So, to use your example of A minor: "A" would be the note that sounds most like home base. It will probably be the last note of the melody. It will use B; C, instead of C# (which would be used in A major), D and E; and either F and G or F# and G# (depending on a variety of things).

You're going to want to study some music theory to be able to write this all down and communicate it to other people; try and take a class, or hire a tutor! And best of luck!