Mother Teresa was born Agnes Gonxha Bojaxhiu in Skopje to Albanian parents. At this time Skopje was under the rule of the Ottoman Empire. At the age of 18, she entered the Order of the Sisters of Our Lady of Loreto in Ireland. She trained in Dublin and in Darjiling (Darjeeling), India, before taking her religious vows in 1937. She took the name Teresa from Saint Teresa of Lisieux, the patron saint of foreign missionaries. While serving as principal of a Roman Catholic high school in Calcutta (now Kolkata), Mother Teresa was moved by the presence of the sick and dying on the city's streets. In 1948 she was granted permission to leave her post at the convent and begin a ministry among the sick.

In 1950 Mother Teresa and her associates were approved within the archdiocese of Calcutta as the Missionaries of Charity. The order was later recognized as a pontifical congregation under the jurisdiction of Rome. Members of the congregation take four vows on acceptance by the religious community. In addition to the three basic vows of poverty, chastity, and obedience, a fourth vow is required pledging service to the poor, whom Mother Teresa described as the embodiment of Christ.

In 1952 Mother Teresa opened the Nirmal Hriday (Pure Heart) Home for Dying Destitutes in Calcutta. She eventually extended her work to many other parts of the world. In recognition of her efforts, Mother Teresa was awarded the Nobel Peace Prize in 1979. She was forced to scale back her activities in 1990 because of declining health. Mother Teresa: In My Own Words, a collection of her anecdotes and quotations, was published in 1996. In 1997, because of Mother Teresa's poor health, Sister Nirmala was chosen to succeed her as leader of the Missionaries of Charity. Later that year, Mother Teresa passed away. People around the world mourned her death.