By default, OS X Mavericks turns on autocorrection. If you're a bad speller then this can come in handy and save you hours of embarrassment in e-mails and other documentation. It can also be an annoyance. I type fast and make mistakes, and some of the time Mavericks is able to correct my mistakes properly. Other times it guesses wrong, substituting words that I've mistyped with something else entirely. If you're having that problem, here's how to turn off autocorrection in Mavericks:
In the top menu bar, Click on the logo and then System Preferences.
Now click on Keyboard.
Click on the Text tab.
Uncheck Correct spelling automatically.
That's it. That's all it takes to turn off autocorrection in Mavericks. This will work with any app that uses system-level autocorrection. If you're using specific word processors like Microsoft Word or Apple Pages, you may have to turn off autocorrection in them separately.