Area is a measurement of the size of a surface.A surface is ( in mathematics and topology ) a two-dimensional manifold.The area term can be used in a non-mathematical context to be mean "vicinity".

The SI unit of area is the **square metre**. The two main systems to measure area are the metric and the English system.

Commonly used units are the *are* , *hectare* and the* square kilometre *, that are derived from the square metre.

In the Imperial system of units, commonly used units of length are the* square foot *, the *square yard*, the* acre *, and the *square mile*.

**Acre (ac or A)** is a unit of area used for measuring real estate in English-speaking countries.It is equal to 4840 square yards. There are 640 acres in a square mile. The "Acre," is an old english word meaning a field and was originally defined as the area that could be plowed in a day by a yoke of oxen.

**Hectare (ha)** is a metric unit of land area, equal to 100 ares . One hectare is a square hectometer, that is, the area of a square 100 meters on each side: exactly 10 000 square meters or approximately 11 959.9 square yards,107 639.1 square feet or 2.471 054 acre.

The term are can also be used in a non-mathematical context to be mean ' land ' or
'geographical area';

This is a list of teritories of the world sorted by total area(total areas are included, covering land and inland water bodies ( reservoirs, rivers,lakes). Marine internal waters, territorial waters and Exclusive Economic Zones are not included):

- Vatican City - - 440 000 m²
- Los Angeles, California, USA - 1290 km²
- California,USA - 423,970 km²
- Russia - 17,098,242 km²
- Republic of China - 9,640,821 km²