There seem to be 3 major themes when it comes to modifiying a civic: JDM, Sleeper, and Rice. JDM (Japanese Domestic Market) characteristics include importing and installing parts from authentic JDM civics (or other japanese honda models) such as side markers, jap instrument clusters, steering wheels, and jap-spec racing wheels (spoon, mugen, 5Zigen, etc. or knockoffs (rota).
Sleeper: A car that remains mostly stock on the outside but has extensive modification to the motor such as a motor swap and a turbo or supercharger. Mild aesthetic and/or performance upgrades are generally suspension modifications (springs, shocks, adj. coilovers, sway bars, bushings, etc) brake upgrades (larger rotors, rear disks, etc), and upgraded, though still factory, alloys (Si, Integra GSR, etc).
Rice: All the rest of the fucking shit you see driving around. "Powered by honda" stickers, ugly altezza taillights, neon glow, heinous body kits (usually unpainted or primered and rarely color matched), stickers so thieves know what to steal, cheap universal mufflers welded to the stock exhaust pipe, cut springs (as opposed to aftermarket springs - you can tell if the springs are cut because the car bounces up and down while it drives on the straightest of roads), etc.
This is the best definition for a honda civic.
If I see another mexican driving a stock civic with a "powered by civic" sticker on the windshield I'm gonna shit.