Compliment and Complement
You’d be very rich if you were given a pound or Euro every time one of these words was misused. Compliment is a verb or a noun and means to say something nice about someone or something.
He complimented his girlfriend on her artistic skills.
Complement is also a verb or a noun and suggests that two or more things go well together
The sofa complements the colour of the wall.
A word to the wise
We could have cited (not sited!) many other examples of English words which cause confusion. Sometimes the differences between these words is nuanced and so errors may not be noticed. However, mistakes can be obvious and completely change the meaning of a sentence. A poor choice of words matters little in casual conversation. But errors could prove to be hugely problematic if they feature in legal documents and instruction manuals.
It pays to find the right words and software won’t always find them!