[Sp5]

One mark of an educated person is knowing your homonyms and using the right word.

I can't help it, when I see mistakes in these words, I discount the writer's intelligence.

Using the right word in a phrase is an indication of education.

First, you start with knowing how to use its/it's, your/you're, who's/whose - the common ones.

There are a lot of other traps, for example:

discrete/discreet

peak/peek/pique

rain/rein/reign

tow/toe

principal / principle

roll / role