Complement: to complete
Complement, spelled with an E, means something that completes or goes well with something else: "The wine complements the meal perfectly." "These two skill sets complement each other."
Compliment: to praise
Compliment, spelled with an I, means a polite expression of praise, or to give such praise: "She gave me a nice compliment on my presentation." "He complimented her on the new haircut."
The trick
complEment has an E, like "complEte" — it completes something. complIment has an I, like "I like it" — it's about praise (something nice someone says about you).
Examples
Complement: "The scarf complements the outfit." "A good side dish complements the main course."
Compliment: "Thanks for the compliment!" "He complimented the chef on the meal."
Frequently asked questions
What's the memory trick for complement vs. compliment?
"Complement" has an E, like "complete." "Compliment" has an I, like a nice thing said to "I/me."
"Complimentary breakfast" — is that spelled with an I or E?
With an I — "complimentary" here means "free, given as a courtesy," related to the "compliment" family.
Can two things "complement" each other?
Yes — it means they go well together or complete each other, like colors, flavors, or skills.
Is it rude to say "I complemented her"?
It's just a spelling mix-up — you likely meant "complimented" (praised her), not "complemented" (completed her).