One of the most natural forms of human expression is singing. It is therefore not surprising that when humans worship the deity they believe in, they sing while doing so. Singing during worship occurs in every religion throughout the world. A hymn, per se, is generally considered the territory of the Christian faith, although other faiths have their own version of the hymn.
A hymn is generally described as prayer or praise to God, set to chordal music, in stanzas and meant to be sung by a congregation. In this sense, the hymn is a blueprint for most Western music. Most popular songs have verses and a chorus, sung with a defined melody line. They take this directly from the hymn form, although not every hymn has a chorus.
The hymn found its origins in Jewish worship as Psalms were sung in the Temple and synagogues. After Christianity became an established religion, these Psalms continued to be popular in churches, since most early Christians had been raised in the Jewish faith. These structures were adapted by St. Benedict in the sixth century, as he worked to develop what is now called Gregorian chant.
Monks and nuns chanted various prayers and the Psalms at certain hours of the day, giving rise to the Divine Office, or Liturgy of the Hours that many orders, particularly cloistered ones, still chant each day. The entire Mass service was mostly chanted. Chant, incidentally, involves singing a certain number of words on the same note, with the tone rising or falling at the end of the line. It is difficult to do well, and takes a great deal of practice. Thus, chant was difficult for the average congregation to fully embrace.
About the time of the Protestant Reformation, a restlessness grew up with the chant, then sung entirely in Latin, the language of the Church. Worshipers wanted to sing in their own language, or "in the vernacular." As the Protestant Church became more established, great composers such as Johann Sebastian Bach wrote beautiful choral pieces, meant to be sung by groups. Gradually, church music progressed to congregations singing many of the songs in the service.
Dr. Isaac Watts is considered the "Father of English Hymnody" and is credited with writing over 700 hymns. His work in the late 17th and early 18th centuries propelled the hymn to a place of reverence and admiration in the church. He penned the words to the well-loved Christmas carol "Joy to the World," and other hymns such as "When I Survey the Wondrous Cross" and "O God Our Help in Ages Past." These are considered some of the great hymns of the Christian church and may be found in nearly every Protestant hymnal.
Other well-loved hymns such as "Amazing Grace" and "How Great Thou Art" are somewhat more modern, and reflect a changing musical tradition. The hymn has changed somewhat in the past 75 years or so, reflecting more of the sounds of secular music. Some worshipers embrace the new hymn forms, while others prefer the classic forms. Both have much to offer and teach a worshiper, or a scholar of sacred music.