Recherche sur Wordpress

Core

https://codex.wordpress.org/Creating_a_Search_Page
https://developer.wordpress.org/reference/functions/get_search_form#comment-content-369

If you do have searchform.php in your theme, it will be used instead. Keep in mind that the search form should do a GET to the homepage of your blog. The input text field should be named s and you should always include a label like in the examples above.