Imagine if Julius Caesar said “I came. I saw. Gaul was conquered by me” instead of “I came, I saw, I conquered.” He took advantage of parallelism to create a powerful sentence. Parallelism means that elements of the sentence are parallel. Here are some examples of sentences that are not parallel to demonstrate the meaning of the term:
I like to walk, swimming, and to dance on the street.
I prefer hockey more than playing baseball.
When elements in a sentence are not parallel, it is distracting for the reader because the sentence is not balanced. In many cases, it even forces the reader to re-read the sentence.
To ensure that your sentences are parallel, just remember that when you start a verb pattern, continue the pattern throughout the sentence. You can make the examples above parallel by continuing the verb pattern.
I like to walk, to swim, and to dance on the street.
I prefer hockey more than baseball.