Acrostic

Quick Overview (courtesy of Wikipedia)

An acrostic is a poem or other composition in which the first letter (or syllable, or word) of each line (or paragraph, or other recurring feature in the text) spells out a word, message or the alphabet.

 The word comes from the French acrostiche from post-classical Latin acrostichis, from Koine Greek ἀκροστιχίς, from Ancient Greek ἄκρος “highest, topmost” and στίχος “verse”.^[2] 

As a form of constrained writing, an acrostic can be used as a mnemonic device to aid memory retrieval.

Acrostics are common in medieval literature, where they usually serve to highlight the name of the poet or his patron, or to make a prayer to a saint.

They are most frequent in verse works but can also appear in prose. The Middle High German poet Rudolf von Ems for example opens all his great works with an acrostic of his name, and his world chronicle marks the beginning of each age with an acrostic of the key figure (Moses, David, etc.). In chronicles, acrostics are common in German and English but rare in other languages.^[3]

Acrostics can be more complex than just by making words from initials. A double acrostic, for example, may have words at the beginning and end of its lines, as this example, on the name of Stroud, by Paul Hansford:

 S et among hills in the midst of  five valley S,
 T his peaceful little   market town we inhabi T
 R efuses  (vociferously!) to  be  a  conforme R.
 O nce home  of  the cloth  it gave its name t O,
 U phill and down again its  streets  lead  yo U.
 D espite its faults it leaves  us all  charme D.

Helpful Links

https://poets.org/glossary/acrostic