What's the difference between carpet cleaning and shampooing?

Hot-water extraction lifts soil out of the carpet pile; shampooing works detergent into the fibers and can leave residue behind that re-attracts dirt. Modern professional cleaning is almost always hot-water extraction — hot water and cleaning solution injected under pressure, immediately vacuumed back out, taking the loosened soil with it. Shampooing is an older method that relied on foaming detergent and mechanical agitation to lift soil to the surface, then vacuum extraction later. When the residue isn't fully rinsed, it can leave the carpet feeling stiffer and can attract new soil faster. For most residential carpet, hot-water extraction is the right choice.