I've been following some news stories on the BBC and some political posts on Facebook (Eff-book) and a lot of opinion pieces on NFL.com.
Reading the comments that follow each, I'm struck by the utter ineptitude of posters to make use of the English language in a correct manner.
Certainly I can make allowances for inaccuracy in spelling for a poster from Guatemala or Myanmar, but from English-speaking countries -- why, it seems that if you want your comment to be taken at all seriously, you would at least spell-check your work. And if spell-check isn't something you believe in, and you don't even know how to say something in print that doesn't make you look like a moron, then maybe ... you don't know enough about anything to comment.
Take your time. Use spell check. And if you are a speaker of English who had/has no interest in accuracy of spelling or grammar or punctuation, then you probably have no interest in researching accurately the facts to support your argument.
In which case, shut up.
They're, Their, and There are not interchangeable, and not the same word.