ASL poetry is poetry created in sign language. Like poetry in any other language, it is an artistic expression of human experiences using the language in a creative way.
Poetry in American Sign Language is expressed with hand signs and facial expressions. As a written tradition in sign language is rather rare, and this was especially so in earlier days, the principal way of saving poetry was by passing it on from one group to another. So, people made up stories and poems and performed them before their peers, and the peers then retained these performances to repeat them elsewhere. In this, of course, some of the originality of the poet usually got lost. However, since videos and the Internet have now became more common, deaf people have taken to recording their creative works and have thus made ASL poetry both easier to preserve and more available to a wider audience than before.
Like in English and other languages, ASL poems come in a wide variety. The poems may be funny, sad, happy, playful, serious, philosophical, and so on. Sign language poets may use accepted signs in their poems or invent new ones as required just as poets in other languages use existing words and make up new ones. In this latter matter, sign language poetry is more flexible than ASL prose.
In order to make or understand this type of poetry, it is necessary to be fluent in sign language and to have an excellent grasp of its linguistic qualities. An ASL poem may lose its edge if translated into English, in much the same manner as an English poem may not seem quite as effective if translated into, say, Spanish.
The poetry is taught in sign language courses like the Narrative and Poetic Styles in ASL course at the University of Rochester and in the ASL Literature course at Gallaudet University.