The phrase "obligatory part" refers to something that is necessary or required. It is something you have to do or include as a part of a particular activity, event, or task.
Sentences with «obligatory part»
They become almost obligatory parts of online efforts to to the extent we almost don't expect them to succeed. (dotearth.blogs.nytimes.com)
West Bank (CNN)- Boarding a bulletproof bus to travel through one of the Middle East's perennial hot spots may not be most people's idea of a fun vacation activity, but for a growing number of Christians visiting West Bank settlements, it's becoming an obligatory part of their visit to the Holy Land. (religion.blogs.cnn.com)