Students at the beginner level often confuse the use of ‘because’ and ‘because of’. In this post I’ll briefly explain the difference between the two, and at the end you’ll find the link to an online grammar exercise on this.
BECAUSE
The word ‘because’ is a conjunction. It introduces a clause, which is a whole sentence containing a subject and a verb. This clauses explains the reason for the statement given in the main clause:
I feel tired because I was working the whole day.
Mark is happy because he passed all his exams.
Sophie is very rich now because she won the lottery last month.
BECAUSE OF
‘Because of’, however, is a preposition. It is mainly followed by a noun (or an adjective + noun combination) or a pronoun:
We didn’t go out yesterday because of bad weather.
She was late for work because of him.
Craig couldn’t travel because of some health issues.
Ready for some grammar practice? To do my 10-question grammar quiz, please click here.
And if you have any questions about this, you’re welcome to post them in the comments sections below!
grammaticus 
Great clarification!
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