Common Errors in English

[FS]

"accidently" (which should be "accidentally") was a long-time pet peeve of mine. I also used to question whether it was "definetly" or "definately", which is how I often saw it spelled on the Internet. Then someone pointed out to me that it was neither.

One thing that has failed to stick by me from my English classes is certain possessive terms. I keep forgetting whether or not, and when, I can use an apostrophe without an "s". Is it Max' or Max's? The Johnsons' or the Johnsons's?

It's an entirely different way of flying! Altogether!