All day and every day

A common mistake made by students is to confuse "all day" and "every day". (In English, you CAN'T say "every days", because "every" is used with a singular noun.)

All day refers to the entire day, or most of it. A shop like 7-11, Tesco Express, or any other convenience store which is open 24 hours, is open all day (and all night!). In summer, you might take your holiday (AmEng vacation) in some place like Valencia, and if you really love to sunbathe, you would probably spend all day at the beach.

When you do something every day, you do it Monday, Tuesday, Wednesday, Thursday, Friday, Saturday and Sunday! Of course, you can also say, for example, that you get up at 6.30 every day during the week, but that at weekends (AmEng on weekends), you get up at 9.00 or 10.00. During the World Cup, there's at least one football game every day from 9 June to 27 June.

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All-day and everyday are adjectives:

When something is an everyday occurrence, it happens very often.

An all-day meeting would probably last at least eight hours.