A family of Microsoft word processing software products for creating web, email, and print documents.
The "backwards P" is called a pilcrow, and Word uses it to represent the (usually invisible) mark at the end of a paragraph. That character also appears on a button on the Home ribbon that, when turned on, makes all the nonprinting characters visible.
In the Find/Replace dialog, when wildcards are not enabled, the paragraph mark is represented by the code ^p. That code and many others can be inserted in the Find What and Replace With boxes by clicking the More button to expand the dialog and then clicking the Special button at the bottom of the expanded section.
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If you have occasion to use wildcard searches, the code ^13 must be used in the Find What box, although ^p continues to work in the Replace With box.