As Wikipedia puts it...
In team sports, the term home advantage (also called home field/court/diamond/ice advantage) describes the advantage–usually a psychological advantage–that the home team is said to have over the visiting team as a result of playing in familiar facilities and in front of supportive fans. The term is also widely used in "best-of" playoff formats (e.g., best-of-seven) as being given to the team that is scheduled to play one more game at home than their opponent if all necessary games are played.
This is particularly common in Football, or Soccer (for Americans) where you actually gain more points from scoring away from your home ground.
Do you really have an advantage in a game like Football where the pitch is standardized? If so what are the real advantages of this? And are they so great that it warrants more points for scoring as an away team.