What are the five obligations outlined by the Prophet in the Koran?

From the text:

“The prophet gave us the Koran, and left us just five obligations to satisfy during our lives. The most important is to believe only in the one true God. The others are to pray five times a day, fast during Ramadan, and be charitable to the poor.” He stopped there. His eyes filled with tears as he spoke of the Prophet. He was a devout man, and, even with all his impatience, he wanted to live his life in accordance with Muslim law. “What is the fifth obligation?” the boy asked. “Two days ago, you said that I had never dreamed of travel,” the merchant answered. “The fifth obligation of every Muslim is a pilgrimage. We are obliged, at least once in our lives, to visit the holy city of Mecca.”