'Groove' as such comes out of the intersection of bass, percussion and the lead rhythm instrument (guitar or keys, typically). It's what you get when you set syncopation among the other instruments (and the bass drum
) against straight four on snare and symbols. Groove has two main effects:
1. It almost demands a physical response - toe tapping, headbanging, dancing, whatever. Groove is felt more than heard.
2. It breaks up the other elements of the song into short, easily digestible phrases that quickly become comfortably familiar (the 'hook').
In other words, groove is the perfect backbone for music that is meant to be commodified, as it basically flips the 'off' switch to the brain.