Ha, one of the units of measurement the level is more to measure the level of land used, and with the symbol HA, is displayed.

each 100 sq. m. a "AR".
"Hecht" suffix Greek meaning 100.
so Ha, i.e., 100 multiplied by 100 sq. m. or in other words, 10٬000 square meters. (100×100=10000)
In fact, the area of a square with side length of 100 meters, a hectare is.