http://www.thefa.com/football-rules.../football-11-11/law-12---fouls-and-misconduct
Direct free kick
A direct free kick is awarded if a player commits any of the following offences against an opponent in a manner considered by the referee to be careless, reckless or using excessive force:
- charges
- jumps at
- kicks or attempts to kick
- pushes
- strikes or attempts to strike (including head-butt)
- tackles or challenges
- trips or attempts to trip
If an offence involves contact it is penalised by a direct free kick or penalty kick.
- Careless is when a player shows a lack of attention or consideration when making a challenge or acts without precaution. No disciplinary sanction is needed
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IMPEDING THE PROGRESS OF AN OPPONENT WITHOUT CONTACT
A player may shield the ball by taking a position between an opponent and the ball if the ball is within playing distance and the opponent is not held off with the arms or body.