Me shouting at a cloud: "every day" means "all days" or, adverbially, "on every day"; "everyday" means "ordinary, common, expected".

I know I'll get downvoted, but I see the conflation of "everyday" and "every day" everywhere and it's driving me bonkers.

ETA: Note, they are pronounced differently. "Everyday" has a single primary stress on the first syllable. "Every day" has two primary stresses, one on the first syllable and one on the last.