Turn Off Mac's Safari Reader

Thank you so much! This is going to be helpful in more ways than one. Your information though will help the various issues I find as I use Safari.

For anyone who may be having a New York Times problem, I did discover a page-by-page fix on the Times site: I click on the white space around the pop-up summary, and I get the page back. I don't know yet whether this is something the Times has done or whether I can fix it through the Mac settings.

Adding to my question: this seems to be happening only on The New York Times website.