Taboos can include a number of actions and utterances.
It depends on the particular location or community involved but certain taboos are commonplace among a widespread spectrum of people regardless of their location and customs. Dietary restrictions are quite common in various religions and this includes Judaism and Islam, where you often hear references to diets which are kosher or halal diets depending on the religion.
Restrictions also exist on a variety of different activities as well which may include activities which are of a sexual or romantic nature and this practice is quite common in a number of different customs. Taboos may also exist on the use of illegal drugs or mind altering substances, taboos also tend to exist in the use of words and obscene language though the actual sort of language varies accordingly.