In the professional world, written communications is the most pervasive method of interaction. On a daily basis, we business people write emails, proposals, analyses and — in the social media age — tweets and status updates. The words we write and share reflect our credibility and level of attention to detail.

Most professionals know to spell-check their writing. But all too often, we make other types of grammatical errors that make us look unprofessional and overshadow the good ideas in our communications.

Below are the twelve most common mix-ups in business writing. Re-learn the distinction between the words to keep your business communications as polished as possible.

1. Affect vs. Effect

  • The rule: “affect” is a verb, while “effect” is a noun. Note: “effect” can be used as a verb when followed by an object. But when in doubt, just stick to the verb versus noun rule.
  • Examples:
    • Viruses affect millions of computers every year.
    • A corrupt file is one harmful effect of computer viruses.

2. Complement vs. Compliment

  • The rule: a “compliment” is a nice comment, while “complement” refers to something that completes or goes well with something else.
  • Examples:
    • My boss often compliments me on my nice hair.
    • I always receive compliments when I wear that red dress.
    • The tagline complements the logo.
    • Cream cheese is a nice complement to cookies.

3. E.g. vs. I.e.

  • The rule: “e.g.” is a Latin abbreviation that means”for example,” while “i.e.” is a Latin abbreviation that means “that is.” Use “i.e.” to specify or clarify a point. Use “e.g.” to provide an example of a point. And remember: always include a comma before and after both of these Latin abbreviations.
  • Examples:
    • I suggested that a yellow potato, e.g., Yukon Gold, would be more appropriate for the recipe.
    • We’re going to the same place we go every summer, i.e., the lake house.

4. I vs. Me

  • The rule: “I” is a subject pronoun, while “me” is an object pronoun. “I” is the subject of a sentence or clause. “Me” is the direct object of a verb in a sentence or clause. If you’re trying to determine which pronoun to use, simply use the sentence with just the pronoun to see if it makes sense.
  • Examples:
    • My colleague and I worked on the project together.
    • The CEO gave awards to the team and me.
    • He likes analyzing numbers more than I [do].
    • He likes analyzing numbers more than he likes working with me.

5. Fewer vs. Less

  • The rule: “fewer” applies to things that can be counted, e.g., candies, while less applies to abstract things or mass nouns, e.g., water.
  • Examples:
    • Supermarket express checkout lanes should read “15 Items or Fewer.”
    • I drank less coffee today so I am less dehydrated.

6. Ironic vs. Coincidental

  • The rule: irony indicates an incongruity in a series of events that result in the opposite of one’s expectation, while coincidence is a series of events that appear planned but are actually accidental.
  • Examples:
    • It’s ironic that Alex moved from Texas to California to escape Texan women, yet he fell in love with a Texan he met in California.
    • It’s coincidental that Alex moved from Texas to California, where he fell in love with a woman from Texas.

7. Its vs. It’s

  • The rule: “its” is the possessive form , while “it’s” is a contraction for “it is” or “it has.”
  • Examples:
    • The company is in its eighth year of operation. Its headquarters are in San Mateo.
    • It’s time to start the meeting. It’s best to round up all the meeting attendees.

8. That vs. Which

  • The rule: “that” is used with a restrictive clause, while “which” is used with a nonrestrictive clause and is always preceded and followed by commas. Restrictive clauses are essential to the meaning of the sentence. Nonrestrictive clauses add further meaning to the sentence but doesn’t change the meaning of the sentence.
  • Examples:
    • Companies that are focused have a higher chance of success. This means that focus is necessary for a company’s success.
    • The new software feature, which was developed by a talented engineer, has been hugely popular with customers. The clause in this sentence gives us more information about the new software feature, i.e., who developed it; however, the point of the sentence is that the new feature is popular. Even if you left out the detail about who developed the software, the meaning of the sentence doesn’t change — the software feature has been popular with customers.

9. Their vs. There vs. They’re

  • The rule: “their” is a possessive pronoun, “there” refers to a place or indicates the existence of something, and “they’re” is the contraction of “they are.”
  • Examples:
    • Their customer support staff is very friendly.
    • There is a customer support staff available 24/7.
    • They’re training additional customer support staff to help customers.

10. Your vs. You’re

  • The rule: “your” is a possessive adjective, while “you’re” is the contraction of “you are.”
  • Examples:
    • Your office has very nice lighting.
    • You’re the happiest employee in the company.

11. Who vs. Whom

  • The rule: “who” is used when it can be replaced with he or she, while “whom” is appropriate when it is used in place of him or her.
    • Who is going to the movies with me? She is going to the movies with me.)
    • Whom are you calling? I am calling him back.

12. Who’s vs. Whose

  • The rule: “who’s” is a contraction for “who is” or “who has,” while “whose” is the possessive form of “whom.”
  • Examples:
    • My cousin, who’s not invited to the wedding, intends to show up anyway.
    • Who’s going to the company picnic?
    • Aunt Bee, whose dog died last winter, is ready to adopt a new puppy.
    • The CEO, whose office is located in the corner, is busy right now.