An acrostic is a prose/poem/puzzle where the first letter* of each line read downwards will make a word or a phrase.
A cross stick?
Can't understand what sir's
Composed a poem instead.
It is nice if the subject matter of the writing is related to the word you choose to compose it on:
Winter, when your warm breath smokes
In the bitter morning chill,
Night brings frosts taht creep and crisp.
Trees are stretching black and still,
Etching patterns where the bright
Robin dares a whistling trill. (Jo Peters)
(*NB - The acrostic word is usually made up of the first letters from each line but it also can also be made up of words from the middle or the end of lines: if two acrostic words appear simultaneously in the same writing it is called a double acrostic, if there are three a triple acrostic and so on )
Enjoy making your own unique poems/proses!