I think we commonly use these words every day but we are not clear which word is correct.
'Everyday' is an adjective. But in 'every day', only 'every' is an adjective.
Everyday means routine, ordinary, standard, etc. Say:
Exercise and clothing mentioned there are 'common' or 'standard.'
On the other hand, the word 'every' modifies the noun 'day' in
'every day'. Say:
He shouts in the class every day.
Since 'every' is used as an adjective, you can use 'every' with other nouns as well! 'Every hour' for instance!
If you are confused, you may apply a trick! Replace 'every' with 'each' and see whether it works!
I read stackexchange each day ~ fine!
I read stackexchange eachday ~ incorrect; there's no such word!