the second and third rule

2. The Ball:
Throughout the time, the rules for soccer regarding the football remained the same, but the way in which they were applied was on a constant change. The rules state that the soccer bull must have a circumference between 68 and 70 centimeters and a weight between 410 and 450 grams but they also state that the ball can be made out of "leather or any similar material".

Well that "any similar material" bit constantly improved over time and nowadays soccer balls reached near-perfection. Almost each World Cup brought a new type of soccer ball, with improved characteristics, although all of them stayed inside the official soccer rules stated in the Laws.

3. The Number of Players:
According to the official soccer rules, a team can bring in 10 outfield players and one goalkeeper on the pitch and can have several substitutes on the bench. The numbers of benched subs as well as the actual number of substitutions that are allowed in a single match vary with the type of the game played. For example, in official matches only 3 substitutions are allowed, with 5, 7 or 9 players on the bench.

In friendlies however, a coach can fit in as many players as he wants on the bench and usually he can also make as many substitutions as he needs. In the past, the official soccer rules regarding substitutions were a lot stricter than this.