Mostly a '70s thing, but it's showed up in other decades as well: when a rock song has a long instrumental lead-in.
- Boston's "Long Time" is preceded by a track called "Foreplay". Interestingly, this is the third track on the album, not the intro.
- Steve Miller's "Jet Airliner" is preceded by an instrumental synth riff that's officially titled "Threshold".
- Though it's considered to be part of the track itself, the synth riff from The Who's "Baba O'Riley" ought to count, particularly given that it's an opening track.