Interior locksets may be called interior knobs, passage locksets, spring-latch locks, or tubular locks.

The type that has a push-button lock on one side, often used on bathroom and bedroom doors, is called a privacy lock.

Privacy—not security—is the operative term. This type of lock is easy to release from the "outside" by pushing a thin nail or sturdy wire into the hole at the center of the knob.

Interior locksets come in many different styles and finishes, from round and oval knobs to straight and curved levers. Prices typically run from $30 to $100.

Though some older homes may have doors equipped with old-fashioned mortise-style locksets, nearly all other interior doors utilize cylindrical locksets.