What to KnowApart (one word) indicates some sort of separation between things, as in "keep those dogs apart.”
A part (two words) refers to one of the units into which something is divided, as in "a part of the story."
How to use 'apart'
Apart (one word) is an adverb meaning “at a little distance” or “away from one another in space or time.” It is used to indicate separation, division, distance, or independence.
We tried to keep apart from the drama.
Our houses are two blocks apart.
Seen apart, the paintings didn’t look like much, but together they created a landscape.
We couldn’t tell the kittens apart until they were several months old.
The old stuffed toy was coming apart at the seams.
Take the puzzle apart before you put it away.
They didn’t want to be apart anymore, so they moved in together.
How to use 'a part'
A part (two words) is a noun phrase formed with the article a and the noun part meaning “one of the subdivisions into which something is divided.”
Even a part of the inheritance would pay for his college.
Soccer is no longer a part of my life.
A part of me wants to go to the party.
The song opening is a part that most people don’t appreciate.
She has a part in the decision making for the department.
Overpricing items played a part in the store’s closing.
What to remember:
When you want the noun, use a part. Otherwise use apart.