Some people find it difficult to distinguish the terms apart and a part as they are similar both in sound and in spelling. However, these two have very distinct meanings and should never be used interchangeably.
The word apart is generally used as an adverb used to denote that “two or more people or things are separated by a distance at a specified distance from each other in time or space.”
“More than 500 miles apart, Donald Trump and Joe Biden debate compassion”
Washington Post“Is this the best birthday surprise ever? Mother is left screaming hysterically after her daughter flies 5,000 miles from England to be with her after two years apart”
Daily Mail“Mentor program helps two people a generation apart build friendship”
ABC News 4
It may also be used to mean “in or into parts or pieces.”
“Ted Cruz, and the speech that threatened to tear the convention apart”
Washington Post
Or “as a distinct item or entity.”
“Simone Biles may be small, but hugely difficult routines set her apart”
SB Nation
Apart is also used as an adjective that means “isolated.” It is either preceded by a noun or found in the predicate.
“On debt and taxation, rich and poor countries are worlds apart”
The Guardian
Meanwhile, the two-word phrase a part is comprised of the article a and the noun part, which denotes “a piece or segment of something such as an object, activity, or period of time, which combined with other pieces makes up the whole.”
“Young Mothers – A Part Of CVS Health’s Success”
Forbes“How guns became a part of American culture”
CBS News“Hydroplanes and pirates were always a part of Seafair — even the first in 1950 (photos)”
Seattle Times
There are two simple ways to determine which term to use in your sentence. The first one is by trying to take away the a and see if it would still make sense. If it does, then a part would be more applicable and if it doesn’t, then apart would be more appropriate.
Correct: Voluntarism is part of the solution.
Incorrect: They spent five years part while he was in the army.
Another useful technique is by remembering the prepositions that they are often paired with. Apart is usually paired with the preposition from while a part is often paired with of.
They couldn’t keep those two dogs apart from each other.
She always felt like she was a part of the family.
Is there anything else that confuses you about apart and a part?