There are a number of two-word phrases that, when combined into one word, cause a shift in grammatical function. For example, set up is a verbal phrase; setup is a noun. Likewise login, a noun (or, in some cases, an adjective), becomes a verbal phrase when written thus: log in.
I bring this up because a depressingly large number of people seem to confuse everyday with every day.
The former is principally an adjective, as in “I need a suit for everyday wear.” The latter is an adverbial phrase: “I smoke three packs of cigarettes every day.”
To demonstrate the difference, here’s Big Joe Turner with Pee Wee Crayton and Sonny Stitt:
[audio:https://helveticka.com/blog/wp-content/uploads/2011/06/04-Every-Day-I-Have-the-Blues.mp3|titles=04 Every Day I Have the Blues]