A hockey pitch is the playing surface for the game of field hockey. Historically, the game was played on natural turf (grass) but nowadays is predominantly played on an artificial turf. The transition onto artificial pitches came during the 1970s and was made mandatory for major competitions in 1976. All the lines, markings and goal specifications are outlined by the International Hockey Federation in "The Rules of Hockey".
All line markings on the pitch form part of the area which they define. For example, a ball on the side line is still in the field of play; a ball on the line of the penalty circle is in the penalty circle; a foul committed over the 23-metre (25-yard) line has occurred in the 23-metre area. A ball must completely cross a boundary line to be out of play, and a ball must wholly cross the goal line before a goal is scored.
Due to the original formulation of the rules in England, the standard dimensions of a hockey pitch were originally expressed in imperial units. The rules are now expressed explicitly in metric dimensions (since 1998) although the use of the imperial terms remains common in some countries.
The hockey pitch is rectangular in shape. The longer perimeter edges are called the side line, the opposing shorter edges are referred toe back line and the portion of this between the goal posts is known as the goal line. The side line must measure 91.40 m (100 yd) and the back line should measure 55.00 m (60 yd). There must be a minimum run-off of 2 m at the sidelines and 3 m at the backlines which may be a different surface for the final metre. All line markings must be white and 75 millimetres wide. In each corner of the pitch, a corner flag of no more than 300 mm square is attached to a post of height 1.20–1.50 m.
Historically, the pitch dimensions were imperial and were replaced by metric equivalents in 1998. The first recorded rules represented what London clubs were using at the time. Surbiton Hockey Club's minutes from 1876 stated that pitches were to be "100–150 yards (91–137 m) long and 50–80 yards (46–73 m) wide". Rules by the Hockey Association of England in 1886 specified "100 yards long by 55 to 60 yards (50 to 55 m) wide". In 1905, the International Rules Board allowed the width of the pitch to be "up to 66 yards (60 m)" but this decision was reversed in 1909. In 1975, the current width of 60 yards was written into the rules.