Linked from
The 38 pages that link to Surfactant, each with the reason it gives.
DetergentBroader topic: Surfactants help water wet surfaces and detach greasy soils.
ToothpasteBroader topic: Surfactants help toothpaste foam and disperse across tooth surfaces.
Hair careBroader topic: Surfactants make oily soil removable with rinsing.
LaundryBroader topic: Surfactant molecules help water wet fibers and carry away grease.