So many thoughtful and talented people have written so well about the development of the daily office, or the Christian duty of daily prayer, that it's folly for me to do so in brief. Indeed, you may want to stop here and get a copy of George Guiver's 2001 Company of Voices: Daily Prayer and the People of God instead.
My job here is to get Unitarian Universalists (and similarly Protestantly reformed sorts) to the doorstep. Inside the house is ninteenth and twentieth century works from our tradition that themselves have roots in the daily office. Together we might make something for the twenty-first.
Christians adopted the practice of praying at different times of the days from Jews, and both made extensive use of psalms. Seven services a day for monks three of which were short and at midday, but we will not be retuning to these. In late antiquity, the peoples' versions would be twice daily, but mainly praises and prayers, with some other scripture: partipatory and jubilant.
In the eastern Mediterranean, say in the seventh century, these prayers were popular among everyday people, as opposed to the priestly work at the altar. Some of the rhythms and text choices laid down then continue to this day. But the fullest development in the West, with the seven service, came in the monastaries, which may have had hundreds (even more than a thousand) monastics, either women and men. Much liturgical material was written in this period. Additional services, say, for the dead plus commemorations of the saints crept into medieval, monastic practices, greatly complicating it. Outside the monasteries, literate (and wealthy) laypeople might have vernacular, practical works of piety and prayer (called primers) while the travelling Franciscans used a reduced and one-volume service book, aptly called a breviary. Onward development often meant simplification.
In 1549, the Church of England adopted its first prayer book, simplifying and formally compressing the services of (overnight) matins and (pre-dawn) lauds into morning prayer, and (after sunset) vespers and (bedtime) compline into evening prayer. Later, elements from (mid-morning) prime was prepended to morning prayer. In each case, transitions persisted, like the breaks between a rail car. (We will examine the contents of the parts, what happens at the breaks and needed reforms later.)
Ideally, this meant morning prayer (with the litany, a long prayer of intercession with alternating parts between the minister and people three times a week) and evening prayer everyday, and communion after morning prayer on Sundays. In practice, the laity did not welcome communion, relegating it to the margins of piety, and the typical Sunday service become morning prayer, with sermon, the litany, trailing into communion but ending halfway.
Colonial Unitarians and Universalists had simpler worship, with heavy doses of preaching, prayers and singing. (The first denominational hymnal in the United States was Universalist.) The King's Chapel (Anglican then Unitarian) and the Menzies Raynor (a New York Episcopanian minister turned Universalist) offer early witnesses to the influence of morning prayer for the Sunday service. When mid-nineneeth-century Unitarian and Universalists (the former influenced by James Martieau) adopted service books, they assumed the standards described in the paragraph above, and these practices influenced others that didn't use the books.