upbeat

Amy Macdonald, Poison Prince:

And what we all want and what we all crave,
Is an upbeat song so we can dance the night away

Upbeat generally means positive, bright and cheery. So we could interpret this line as a craving for a cheerful song, which would make one dance all night long. Too easy?

But wait a minute. Isn't it also something from music theory? Right.

Most of the rock music uses the 4/4 meter, which simply means we can count like one - two - three - four and back to one, and on and on, while listening to the song. Or one - and - two - and - three - and - four - and - and so on. This pulses, all these ones, ands and twos are actually called beats, and usually in rock we have ones and threes accented, like that:

one - and - two - and - three - and - four - and -

Ones, twos, threes and fours are downbeats, while ands are upbeats. When playing the guitar, one note on each beat, you will most probably play numbered beats using downstrokes, and ands - using upstrokes.

You can also accent upbeats:

one - and - two - and - three - and - four - and -

Thus achieving more dynamic and cheery feeling of the song. And this gives us another idea what could upbeat song mean.

By accident or not, but this song is exactly like that :)