What is "?s=" and why is it on my site?

Was running screaming frog on one of my sites, and saw that it is registering a bunch of duplicates. For every page/post, I see a version with a ?s= on the end. For example:
https://www.mysite.com/blog/
https://www.mysite.com/blog/?s=

It isn't like I have two blog pages in the dashboard, so it isn't something I did by accidentally duplicating stuff.

So, what is ?s= and how do I get rid of it?

If you're using WordPress then the ?s= is used for searching.
For example, www.yourblog.com/?s=Christian%20Dating would search your entire blog for "Christian dating".

The search results page essentially becomes another page on your site and it is a good practice to noindex your search results pages.
https://kb.yoast.com/kb/noindex-for-special-pages-in-yoast-seo/

O Google webmaster tools you can tell googlebot what the s parameter does. If it's causing lots of duplicates, you can tell google to ignore it.

Thanks very much you two for the helpful guidance...I'll get it sorted now.