Singing/music and its messages

[Chibi Jen]

I've noticed in some anime, there seems to be some singing involved which they say conveys messages... is that something that happens in real life, or just appears in anime/manga? XD

Also, it seems like in a lot of anime, characters sing, eg Card Captor Sakura, Ranma1/2, Ayashi no Ceres, Fushigi Yugi, Ah! My Goddess, Sailormoon, Love Hina etc Is music/singing something symbolic in Japan, or is it purely to sell CDs? (though not all songs are turned into CDs)

[Death Soldier]

I wonder that sometimes too ^^; Since u've watched Nana..did that convey any messages? (or was the song not subbed? )

I would think that songs generally convey a message..u know how some songs are written dedicated to someone etc? Who sings in Ranma1/2? or you just referring to them singing in the christmas OVA?

Sailormoon- Starlights are there to convey message, but dunno about Rei in the R series ^^;