Why did people undertake pilgrimages during the middle ages?

Quick version Pilgrimages were important in the Middle Ages because Christians believed that bringing themselves as close to God as possible by traveling towards a physical place was the ultimate spiritual act, and they did so in order to fulfill a vow, ask for a miracle cure, deepen their own faith or expiate a crime committed. Christian pilgrimages occurred most often during the Middle Ages; however, there are many other religious groups that go on pilgrimages, including Muslims.