Recognize an infinitive when you see one.
To sneeze, to smash, to cry, to shriek, to jump, to dunk, to read, to eat, to slurp—all of these are infinitives. An infinitive will almost always begin with to followed by the simple form of the verb, like this:
to + verb = infinitive
Important Note: Because an infinitive is not a verb, you cannot add s, es, ed, or ing to the end. Ever!
Infinitives can be used as nouns, adjectives, or adverbs. Look at these examples:
To sleep is the only thing Eli wants after his double shift waiting tables at the neighborhood café.
To sleep functions as a noun because it is the subject of the sentence.
No matter how fascinating the biology dissection is, Emanuel turns his head and refuses to look.
To look functions as a noun because it is the direct object for the verb refuses.
Wherever Melissa goes, she always brings a book to read in case conversation lags or she has a long wait.
To read functions as an adjective because it modifies book.
Richard braved the icy rain to throw the smelly squid eyeball stew into the apartment dumpster.
To throw functions as an adverb because it explains why Richard braved the inclement weather.