There is a transitive and an intransitive version of "treiben".
The transitive "treiben" generally means imparting a more or less constant movement to somebody, in the sense of chasing or startling them, or something, mostly of a more abstract kind, as an occupation, a craft, a sport, etc.
Ich treibe Sport (I do sports; I think practise isn't a bad equivalent here)
Was treibst du so? (Anything from "What have you been doing lately?" to "Long time no see")
Du treibst mich zur Verzweiflung ("You're driving me to desperation", "You're driving me mad")
Du treibst es zu weit (you go too far)
es miteinander treiben (having sex)
Die Bäume treiben Blätter (the trees are branching), Knospen treiben (to bud)
Metall treiben (Metall mit dem Hammer etc. bearbeiten, shaping or embossing metal)
It's more frequent with prefixes, e.g.:
antreiben (to impel, push on)
betreiben (to keep a facility, plant, workshop, business etc. going)
austreiben (e.g. böse Geister austreiben, to cast out evil spirits)
eintreiben (e.g. Geld eintreiben, to collect money by force)
auftreiben (e.g. Geld auftreiben, to raise money, jemanden auftreiben, to find somebody)
The intransitive "treiben" means floating, thus being moved (den Fluss hinunter treiben) or just staying afloat (an der Wasseroberfläche treiben).
austreiben (die Blätter treiben aus)
In between a transitive and an intransitive meaning goes the idiom "sich treiben lassen", which is something like drifting without a goal.