A common source of confusion about contact lenses involves replacement and removal intervals. There are two basic schedules for putting on and taking off your contacts - replacement schedule and wearing schedule.
Replacement schedule refers to how often your lenses are discarded and replaced — that is, whether they are disposable, frequent replacement or reusable. Wearing schedule refers to how often you remove your contacts (but don't necessarily discard and replace them). Daily wear means you remove them each night. Extended wear means you sleep in them. Disposable contacts can be prescribed either for daily wear or extended wear, depending on your eye physiology and needs.