There are in fact several forms of indoor football. Futsal, indoor football and indoor soccer are slightly different but the essence is the same. These kinds of soccer are considerably more dynamic and the game tempo is faster than that of regular soccer. This can be accounted for by several reasons. The field size is much smaller and weight and size of the ball is also different. Indoor soccer rules are similar to those of regular football , but nevertheless there are a few differences.
There are specific requirements as far as the dimensions of the playing area of indoor soccer are concerned: the length should not be less than 175 feet, nor more than 210 feet; the width of the playing field should not be less than 75 feet, nor more than 100 feet. 85 feet in width and 200 feet in length is the recommended size of the playing field.
Indoor soccer requires that the playing field have special markings, namely distinctive white lines (except for yellow lines the purpose of which is explained below). The white lines are markers of the playing field; the width of the white lines is also concrete, they should be not more than five inches (5") nor less than four inches (4") in width. It is a conventional standard that a perimeter wall that is part of the playing field should circumscribe the goal and touchlines.
Across the field of play the halfway line should be marked out. The center of the playing field should be covered by a circular (9") nine-inch red mark and a special center circle with a (15') fifteen-foot radius should be indicated from this mark center. A (50') fifty feet yellow line marking should be placed across the playing ground from each goal line.
Now a few words about the penalty area. At both ends of the playing field two lines should be placed from the right angles to the front line outside of both goalposts. Those lines should be measured (8') eight feet from the inside of both goalposts. These should extend into the playing field for a twenty feet (20') distance. From the middle between the ends of lines, a semicircle with a fifteen feet (15') radius should be placed. This is where the two lines from the right angles to the front line meet. The area marked by the front line and these special lines and the area within the goal is referred to as the Penalty Area.
Indoor soccer playing area can be characterized by special marking of the corner mark and flag. The top of corner flag should be raised (3') three feet above the wall perimeter, should be placed at a spot along the wall perimeter at each corner of the playing field measured (20') twenty feet from the place of the nearest goalpost. A red (9") nine inches in diameter corner mark should be placed (3') three feet inside the wall perimeter, perpendicular to the corner flag and directly below.
In the indoor soccer the goals should be placed on the both goal lines within the wall perimeter and should contain two upright posts that are placed on the same distance from the corner flags united by a special horizontal crossbar. The lower edge of horizontal crossbar should be on the distance of (8') eight feet from the carpet surface.
Like in regular football there exist a lot of indoor soccer leagues, the most popular of them are German indoor soccer league and Spanish indoor soccer league.