Misspelling is rampant on the Internet. The 10 frequent fumbles listed below attest to that.
For fun, I did a search for the incorrect version of nine of the 10 words in this list. I didn’t bother with No. 7 because both its and it’s are valid spellings. The number of hits for the misspellings is shown in parentheses. Some refer to intentional misspellings on writing guidance sites such this one, but most are earnest errors.
(Note: Any spell-check program ought to catch most of these for you. However, the wisest course is to master them yourself.)
How many of these do you see in the course of a week?
The verb is argue, but the noun is argument.
The register on which you schedule your appointments is spelled calendar. Yes, there is a specialized term spelled calender that refers to paper production, but I doubt that it accounts for millions of uses.
There are three e‘s in cemetery. Nary an a in sight.