Selling songs for ads

[crossways]

Has anyone here ever had there songs played in ads?

 

I know one band around here who had a song running with a local custom shop.

 

I was wondering what the process is for that. Is it mostly a deal where a company hears the song they like and contacts the songwriter?

 

Do songwriters contact companies with their songs and shop them that way?

 

Do you need to be in contact with the advertising agencies?

 

Thanks