There are many references in the Qur'an as to what are permissible, or halal, actions and elements of a Muslim's life. These laws are most commonly apply to food, drink and matters of finance and make up part of Shari'ah, or Islamic laws.
Pork, snake (or anything with fangs) and road kill are a few types of meat not allowed.
The ban against drinking alcohol comes from a Divine command, explaining that any intoxicating or mind-altering substance whether it be drugs or alcohol, is not permissible by God. A Muslim prays five times a day and must always be spiritually clean and ritually pure for this act of worship as well as any other part of a Muslim's daily life.
Even banking is affected by what is permitted in the Qu'ran. Muslims have their own way of handling finance that is consistent with Islamic law such as the prohibition of usury, or interest-based finance where the taking of or charging others interest is explicitly forbidden.