Choosing a door-handle for inside your house

There are three general types of door handles that are particularly suitable for inside your house, and before choosing a handle, you need to decide what you would like the handle to do: open and close the door by turning, provide privacy, or simply open the door without any latch. 

Passage door knobs include a basic latch that allow you to open and close the door.  They do not have a lock.  You would typically use this for something like a hall-cupboard, lounge or child's bedroom.

Dummy door knobs can be used to open or close a door but do not include a latch.  They can be used on built-in wardrobes and sliding doors.

Privacy door knobs have both a latch that the door handle operates, but also include a lock on one side.  You would use this for bathrooms or bedrooms requiring privacy.  The lock has emergency access from the outside.