If I may, Ghost of Chaos, I might try to explain:
The word "it" is a pronoun—most often times used to represent quite a lot of things (inanimate objects, groups, activities, a person, etc.). The function of "it" is to replace or substitute nouns and noun phrases that have already been mentioned, or will be soon. Doing so helps from having to repeat oneself over and over again. Other pronouns could be "he/him (substituting a male person), that, this" and a good deal others. Does that make sense?
Now, the word "its" (with no apostrophe, but still an 's') is, in fact, the possessive form of the word "it". For instance, if you were to say: "Bob finally grabbed the chicken's leg", and then you were to substitute the noun "chicken's" with the pronoun "it"—stay with me here—the sentence would look like, "Bob finally grabbed its leg."
In searching for the reason why there is no apostrophe here, I have to take you to a slightly different lesson on pronouns.
Okay, so we know that a pronoun is a word that you can act as a substitute for the actual noun being used, right? A possessive pronoun is simply a word in pronoun form that also acts to designate possession about something to that word.
In the third person, we have "his, her, hers, it" for the singular. "Their" and "theirs" would be for plural.
In the second person, we have "your, yours" for singular and plural.
In the first person, he have "my, mine" for singular, and "our, ours" for plural.
Note: What we have to realize here is that no possesive pronoun contains an apostrophe. Therefore, the possesive pronoun "its" should not either.
In all honesty, the exact reason why there is no apostrophe between the 'it' and the 's', I'm not 100% sure of. Without taking a lot more time to research this, which I just might do, I could assume that the English Language is grouping the possessive pronouns to have no apostrophe—which just so happens to accommodate the actual meaning for "it's" (with an apostrophe).
Okay, now onto "it's". The word "it's" is a contraction of "it is" or "it has". This word's existence is solely to shorten those two word phrases. Instead of saying, "It is not my turn," a person could say "It's not my turn." Or "It's been nice meeting you," in place of "It has been nice meeting you." See what I mean?
This is a rough base line for an answer; do you have any more questions about this?
< Message edited by Master Samak -- 11/29/2009 18:30:40 >