"Peter Piper" is an English-language nursery rhyme and well-known alliteration tongue-twister.

[1] The traditional version, as published in John Harris' Peter Piper's Practical Principles of Plain and Perfect Pronunciation in 1813, is: Common modern versions include: The earliest version of this tongue-twister was published in Peter Piper's Practical Principles of Plain and Perfect Pronunciation by John Harris (1756–1846) in London in 1813, which includes a one-name tongue-twister for each letter of the alphabet in the same style.

[3] Some authors have identified the subject of the rhyme as Pierre Poivre, an eighteenth‑century French horticulturalist and government administrator of Mauritius, who once investigated the Seychelles' potential for spice cultivation.

[4][5] The Peter Piper Principle is a cognitive error that people make, where they tend to confuse two words that resemble each other; in particular, when the first letter(s) are the same.

[6][7] Novelists are well aware of the peril of giving two characters names that start with the same letter, because readers have a tendency to get them confused.