A rugby league team consists of thirteen players on the field, with 4 substitutes on the bench. Each of the thirteen players is assigned a position, normally with a standardised number, which reflects their role in attack and defence, although players can take up any position at any time. Players are divided into two general types, forwards and backs. Forwards are generally chosen for their size and strength. They are expected to run with the ball, to attack, and to make tackles. Forwards are required to improve the team's field position thus creating space and time for the backs. Backs are usually smaller and faster, though a big, fast player can be of advantage in the backs. Their roles require speed and ball-playing skills, rather than just strength, to take advantage of the field position gained by the forwards. Typically forwards tend to operate in the centre of the field, while backs operate nearer to the touch-lines, where more space can usually be found. Names and numbering The diagram, right, shows the typical positions of each player during a scrum (not to scale). The laws of the game recognise standardised numbering of positions. The starting side normally wear the numbers corresponding to their positions, only changing in the case of substitutions and position shifts during the game. In some competitions, such as Super League, players receive a squad number to use all season, no matter what positions they play in. The positions and the numbers are defined by the game's laws as: Backs 1 Full Back 2 Right Wing Threequarter 3 Right Centre Threequarter 4 Left Centre Threequarter 5 Left Wing Threequarter 6 Stand-off Half or Five-eighth 7 Scrum Half or Half-back Forwards 8 Prop 9 Hooker or Dummy-half 10 Front Row Forward 11 Second Row Forward 12 Second Row Forward 13 Lock Forward In practice, the term 'front row forward' is very rarely used, and a team has two props. The scrum half is often known as the half back, especially in Australasia, and the lock forward is usually known as loose forward in England. Backs There are seven backs, numbered 1 to 7. For these positions, the emphasis is on speed and ball-handling skills. Generally, the "back-line" consists of smaller, more agile players. Fullback Numbered 1, the fullback's primary role is the last line of defence, standing behind the main line of defenders. Defensively, fullbacks must be able