How do artists (musicians) make the tune of their song?

different inspirations, it can be visiting a wonderful place, an experience or even meeting new people. But there are cases, like you said, when a melody comes humming. One example is how Steven Tyler from aerosmith composed a melody for the hit single 'Jaded'

It can happen that way on some occasions but what typically happens is one guy has been noodling around with his instrument. Let's say its the guitar and he has something catchy he figured out.

Then another guy lets say the bassist then starts experimenting on top of that tune. And that can be the start of the entire song.

Then knowledge and experience kicks in and then you're figuring out where the song is going to.

Actually the scene in "School of Rock" when Zach reveals that he has a song is how it happens alot of the time. There's also point in that scene where Jack changes the lyrics and asks the background singers to hop in. In that case he used his "mental library" of music knowledge to improve the song. It happens pretty much like that.

Also, sometimes the lyrics dictate the melody sometime the melody dictates the lyrics.

It can happen anyway you can imagine it. Even starting with humming.

sometimes i will just play a note or chord on my guitar and just try to think of what should come next. other times i will write lyrics and melody and then think of the background music. sometimes i will create a beat on my drum machine and just improvise the music. sometimes whole songs just pop into my head from out of nowhere. i would say mostly from improvisation, then hashing out the arrangement and lyrics. i've been writing songs for 20+ yrs and never thought about how i do it. thanks for asking your question!

http://brainstormtroopers.com/

i have thought of songs sitting down drumming with my fingers at a table