In Islam there are some obligatory prayers and actions that Muslims have to take part in, which are called fard. This isn't unique: Many religious practices have actions or prayers that you have to do as part of that religion.
Fard is a word which comes from Arabic, but which has Persian influence. It refers to a religious duty, particularly one that comes from the Qur'an, and that duty can be a prayer or an action such as charity. It doesn't just refer to things a person has to do, but it also refers to things that the community has to do as a whole.