This is a simple difference. Why does it make an appearance here? Well, this simple looking difference actually causes a number of problems.

To keep it short, these two terms stand for the following:
Every day: each day or daily: ‘I have two eggs every day’.
Everyday: commonplace: ‘That dress is perfect for everyday wear’.

In grammatical terms, the word ‘every’ in ‘every day’ is an adjective that modifies the noun ‘day’. The phrase in general functions as an adverb.

Tool tip to remember the difference:

Just Remember: Try to replace everyday/every day with each day. If it makes sense, use every day else use everyday.

Examples of incorrect uses of Every day and Everyday:

1. They had the learner’s program everyday.
2. Team work is an every day occurrence.

Examples of correct uses of Every day and Everyday:

1. I download a new wallpaper every day.
2. He is incapable of handling everyday issues.

‘Every day’ means each day or daily: “At employees have two breaks for snacks every day.”
‘Everyday’, on the other hand, means ordinary, typical, or usual: “Rains in Bombay seem like an everyday occurrence.”
It is also used in the sense ‘something that is used or seen daily; suitable for daily use’: “One should not let everyday problems to overpower oneself.”

Every day something happens that makes me wonder if I should expect everyday errors as the norm.