How to recognize parallelism
Parallelism is a rule of English grammar that demands consistency in a sentence's structure. Any lists of ideas, places, activities, or descriptions that have the same level of importance – whether they are words, phrases, or clauses - must be written in the same grammatical form. Some examples:

activities: running, biking, and hiking
places: the store, the museum, and the restaurant
ideas: how to read, how to write, and how to learn
descriptors: quickly, quietly, and happily

Note the grammatical consistency in each list. The activities all end in "-ing;" the places are all preceded by the article "the;" the ideas all begin with "how to;" the descriptors are all adverbs. In each list, whatever grammatical form is applied to one item is applied to all items. This rule (what applies to one must apply to all) is pretty much all you need to remember.