Requisite,  Prerequisite,  and Perquisite

Does your job come with perks? The word perk comes from perquisite—not to be confused with prerequisite. Those two words can be quite a mouthful and easy to confuse.

Let’s take a look at these three similar-sounding words:

• Perquisite: A perk is a privilege or benefit given in addition to salary. Those season tickets to the local baseball team and discounts on company products are perks or perquisites. Employers are not required to provide them, and it’s probably best if you don’t consider them either a prerequisite or a requisite if you’re job hunting.
• Requisite: This means requirement. Prerequisites are conditions that must be met prior to an event or opportunity. Both carry the idea of something needing to be in place before something can occur. Prerequisite includes a time element, requisite does not.

Thus you would correctly say: Algebra I is a prerequisite for Calculus. Students must demonstrate competency in a lower level math course before they are allowed to take a more advanced course.

Prerequisite can be used as a noun (as in the Algebra-Calculus example) or an adjective. When used as an adjective, follow it with the preposition to.

• The satisfactory completion of Algebra I is prerequisite to enrollment in Calculus.

Understanding the differences between these three words is a prerequisite to being able to use them correctly.