You may not notice it yourself, but if you don't know the difference between YOUR and YOU'RE, you come across as an idiot whenever you use them.  They are not interchangeable, and neither are THERE, THEIR, and THEY'RE, nor any of the examples explained below.  As more and more communication takes place online  and in writing, through chat, email and messaging, certain common misspellings of words and contractions have become dangerously frequent, reinforcing their repeated misuse.  This page doesn't aspire to make you a decent writer, or even a competent speller.  It only seeks to keep you from making an ass of yourself.

YOUR ≠ YOU'RE

ITS ≠ IT'S

THERE ≠ THEIR ≠ THEY'RE

*NEW*     ACCEPT ≠ EXCEPT  *NEW*

NOUNS ≠ NOUN'S

WHO'S ≠ WHOSE

KNOW ≠ NO ≠ NOW

TOO ≠ TO ≠ TWO

OUR ≠ ARE

WHERE ≠ WE'RE ≠ WERE

AFFECT ≠ EFFECT