If you grew up speaking English, you probably remember suffering through Beowulf in school. You may have even enjoyed it, or vaguely recall something about kennings or caesuras.
There's a lot more to Old English poetry than Beowulf, though. The verse form used by the poet of Beowulf, sometimes misleadingly called alliterative verse, is the only form of poetry native to the English language. It was a primarily oral form for most of its history, and so it's very different from the French-influenced forms that later dominated English poetry.
It's one of my favorite styles, both for plain poetry and for writing background verse for stories. Even though the English language has changed almost beyond recognition in the past fifteen hundred years, the old poetry styles still mesh best with its sounds and stress patterns. Also, because the poems were usually composed while they were being spoken, it's suited for fast narrative composition. The style is really very simple. There are only three essential elements: stress pattern, pauses, and alliteration.
The stress pattern may be the most important element. Most people may be familiar with the formal patterns like iambic pentameter, which were inherited through the French. The old English stress patterns are much simpler. Each line is divided into two half-lines, and each half-line contains two strongly stressed words. For most purposes, it doesn't matter how many unstressed syllables there are in each half-line, or where they are. Some more recent poets, such as Ezra Pound and Gerard Manley Hopkins, have re-adopted this method of patterning stresses, sometimes calling it sprung rhythm. It gives poems dignity and musicality without risking descent into singsong.
The second important element in this style of poetry is the way the natural pauses fall in the lines. These pauses are sometimes referred to as caesuras; they're places where it would be natural for the poet to take a breath, or where a punctuation mark falls. A caesura occurs after every two half-lines or every four strong stresses. For some reason, all modern editions place the caesura in the middle of the line, with two stresses before and two after. Actually, in the oldest manuscripts, there are no line breaks at all; only the caesuras are marked by /. It seems more natural to me to break the lines at the caesuras; it's certainly more natural to write that way!
So the poem consists of half-lines, two stresses each, with a natural pause after every two half-lines. The alliteration is what unifies the poem and pulls the half-lines together, but it's actually the least important element. There's much more room for poetic license here. Alliteration is just repetition of the first sound of words; in Old English poetry there are also a few standard cheats: all vowel sounds alliterate with each other and with h and y; wh and w match, and so do s and sh. The only required alliteration is that the last stressed word before the caesura must alliterate with the first stress after it. If it's convenient, the other stress in each half-line can also match; but the unstressed syllables don't alliterate.
There are as many different forms of alliterative verse as there are of more familiar rhymed verse. Poems can be any length, from one-line riddles to novel-length epics; a common variation with shorter form was the use of a repeated refrain, or a recurring pattern of lines with fewer stresses. Later poets often mixed modern rhymed stanzas with traditional alliterated ones, which can be very powerful if the balance is right.
I encourage everyone to take time to explore a beautiful, versatile, simple style of poetry that does not get nearly the attention it deserves!
I originally wrote this for the May/June 2002 issue of Holly Lisle's Vision, an e-zine for writers.