Lock/Knob Assemblies (locksets), the simplest (and least effective) locks, are the kinds which are included as part of the doorknob assembly. They are a great place to start since most doors need knob/latch assemblies anyway; however, more effective locks for exterior applications should supplement them.

A "privacy lock" has a lock on the inside knob only, and is usually used for installation on bathroom or bedroom doors. A "key-in-the-knob" lock, on the other hand, characteristically has a key slot on the outside knob and a button or "thumb turn" on the inside. Key-in-the-knob locks are most often used on exterior doors, although they may also be used on closets or storage room doors where security is a concern.

Assemblies for these locks are called "locksets," and consist of knobs or handles, a latch bolt assembly, and any associated trim--in other words, the entire door knob/lock assembly. They are easy to replace, but an original installation is a bit more challenging since it requires precisely cutting and mortising holes into which the assembly will fit.