There are many things that have been prohibited in the Qur'an and Sunnah. Every Muslim is commanded to learn his deen (religion) in general and these porhibitions in particular. The Qur'an and Sunnah commands are definitely for virtues and their prohibitions are surely malicious deeds that a Muslim should avoid in his everyday life.
Allah and His Messenger have prohibited everything that contains any sort of harm or evil. These prohibitions vary in their degree of evil. They are either haram (un-allowed) or makrooh (abominable) sins, which are also un-allowed even if their degree of evil is less than that of the haram ones; and a true Muslim should avoid both.
This valuable book of al-Munajjid, like his previous book (Muharramat), is a good approach toward understanding these prohibitions of Islam and seeking the ways to avoid them.