A freezer can be part of a refrigerator or a separate appliance. The temperature inside a working freezer should be below the temperature at which water freezes -- 32 degrees Fahrenheit or 0 degrees Celsius. Some freezers are colder or designed to freeze items quickly such as ice cream.
When a freezer is part of the refrigerator, it is usually a separate compartment and has its own door. That compartment can be the upper section, lower section or one side (usually the left side). Sometimes in smaller or less expensive refrigerators, the compartment may not have a separate external door, but a door within the refrigerated compartment.
Food establishments like a restaurant or processing plant may have entire rooms designed to stay below freezing and hold food for storage -- a walk-in freezer.
A freezer is more efficient when it is full. If it is relatively empty, each time you open the door, the cold air flows out. An easy way to fill the space is to put a closed container like an empty, closed plastic milk bottle in the freezer. It's not necessary to fill the container with water to make ice; the air inside the closed bottle will chill to the freezer temperature.
Some of the options to consider when selecting a freezer are size. You can also buy a freezer that is separate from the refrigerator, if you have the room and money and want to store that much frozen food.
Freezers that come with the refrigerator may be placed in different ways (as discussed above).
Some freezers have options like automatic ice makers.
- Wikipedia's article on refrigerator
- Wikipedia's article on ice box