For the grammatically impaired
May. 11th, 2009 08:43 am"When will people learn the difference between laying and lying. You are lying on your bed, not laying. You lay something else down, but you lie [yourself] down.
Who or whom: It's whom did you see, not who did you see. It's who did this, not whom did this.
Answer the question in your mind. If the answer is him, it's whom, if the answer is he, it's who.
Its and it's. If they are 2 words, it's it's. If its meaning is belonging to it, it's its."
Source here and further explanation here.