In c. 400 AD St. Augustine defines the hymn:
Know you what a hymn is? It is a song with praise of God. If you praise God and do not sing, you do not utter a hymn: if you sing and do not praise God, you do not utter a hymn: if you praise anything else, which pertains not to the praise of God, although you sing and praise, you utter no hymn. A hymn then contains these three things, song, and praise, and that of God. Praise then of God in song is called a hymn.
Throughout history, every Christian movement, every generation, brings with it fresh songs of praise and worship, serving as cultural and historical indicators of what the Lord has been doing in His people at the time.
Jesus and the disciples sang the “Passover Psalms” (Ps. 113-118) at the Last Supper.
When the Bible was available only to the learned priests in the Middle Ages, sacred songs sung in Latin, the Gregorian chant (or plainsong), emerged.
An emphasis on doctrinal truths and congregational singing in the 1700s paved the way for hymns from the “Father of Hymnody”, Isaac Watts (Joy to the World), and the “Forgotten Wesley”, Charles Wesley (Hark! The Herald Angels Sing). Author of approx. 8,989 hymns, Wesley believed that hymns should stir the congregation and reinforce its religious emotions.
Revivalist camp meetings spread throughout Europe and America in the mid-to-late 1800s bringing forth the “Queen of Gospel Song Writers”, Fanny Crosby (Blessed Assurance, Jesus is Mine), author of 8,000+ hymns.