The most basic of doorknobs is simply a protrusion on a door which provides a place for a hand to grab in order to pull the door towards you. However, most households prefer to use doorknobs which incorporate a mechanism which ensures the door remains closed until the mechanism is activated.
Doorknobs with this mechanism in work by use of a latch which extends from within the door into a recess in the frame This ensures that the door cannot be pulled open or perhaps blown open by a draft, but that the knob must be turned in order for the mechanism to work. The turning of the knob causes the latch to withdraw into the door itself, removing the blockage between the door and the frame and allowing the door to be opened. It is possible for knobs such as these to also incorporate a lock into them, which works by preventing the action of turning the handle. Generally these are in the form of a button in the centre of the knob which must be pushed in, or twisted depending on the style of knob, and which then stops the handle form being able to be turned. This is the simplest form of lock and can be useful in rooms such as bathrooms as they are simple to operate and means an additional lock does not need to be installed. However, there are cases where an additional lock can be beneficial, for example if the door is external, in which case a mortise lock is always recommended for security reasons.
These doorknobs are thought by many to be the only option as they fulfil all the criteria of a door handle. However, there are occasions when a different style of handle may be beneficial. Because these knobs require a good grip in order to turn them they may be difficult for elderly people, or those with grip problems, to utilise easily. They may need to use two hands to operate the knob which is not always practical, for example if they are carrying something. If the knob is situated close to a wall it may also cause problems as you may find yourself making contact with the wall when turning the knob. In these situations you may be advised to use a lever-style handle.
These work on the same mechanism as the door knob but they are operated by use of pressing down on a lever. This is often much easier for the majority of people to use as it relies not only on the power of the individual but also on gravity and the laws of physics regarding levers. They do not require you to have a firm grip on them either, so those who find gripping objects difficult should be able to use them much more easily.
When considering which handles to buy it is wise to bear in mind the people who you think may be using them before you make your final decision.