A song is a group of musical words, phrases, or sung notes performed by a singer or group of singers with or without instruments (a cappella). A singer may sing alone, with an acoustic guitar, pianist, organist, or accordionist, or in a larger ensemble including other vocalists. A song may have one melody with simple lyrics, complex chord progressions, or even a full orchestral arrangement.
Often, an idea for a song comes to songwriters seemingly out of the blue. Then, as songwriters hone their craft, they solve musical and lyrical problems to make the idea into a song. This process can take years before a song is finally released to the public.
Song writers are encouraged to experiment with the structure of their songs, using a variety of traditional and not-so-traditional formats such as AABB, AABA, ABACBA, AABABCB, and ABCABCB. The most successful songs seem to have some sort of structure that holds the verses and choruses together and a bridge or other contrasting section to break up the repetition.
Another great way to add interest and variety to a song is to modulate, or change key. The most common modulations are up by a half or whole step, which tend to create tension and excitement. The key of a song can also convey a particular mood, with major keys often being interpreted as happy or upbeat, and minor keys being seen as more melancholy or emotional. The lyrics and melody of a song can also be varied by varying the rhyme scheme or rhythm of the lines.