Hymn is a song of praise. In ancient Greek culture, a hymnos was musical praise directed to the gods or heroes of the day. In Christianity, hymns are directed to the one true God, of course.
God’s people have sung hymns in honor of the Almighty since the time of Moses and before (Exodus 15:1). David sang the “new song” God gave him and taught others to sing “a hymn of praise to our God” (Psalm 40:3). Jesus and His disciples sang a hymn together at the Last Supper (Mark 14:26). The early church sang hymns as part of their regular gatherings (1 Corinthians 14:26). Paul and Silas, with their feet in stocks in a Philippian jail, were “praying and singing hymns to God” (Acts 16:25).