It seems as if many in the world have forgotten what the rules are for "it's" versus "its." I see errors in places where you'd have to figure they should know better. Ad copy. Newspaper stories. TV crawls.
"It's" is a contraction for IT IS. "Its" is a possessive, as in, "The dog chased its tail so many times there was a funnel in the floor where it used to go in circles."
I wonder about "It's" as a contraction for "it has." Maybe I was in the bathroom in school that day when Sister Mary Thorn-In-The-Crown Jesus Wore explained that one. It seems correct, as in, "It's been seven lonely years since the dust storm blew away my family."
Some contractions are pretenders: "I'm" for "I am" only saves one space. Who thought that up? It is hardly efficient. (You thought I'd use "it's," didn't you?)
"Couldn't" - another loser. Maybe it has to do with how people mumble? "That's" saves only one space. Stack those spaces up and you aren't going to hit the moon quickly, that's for sure.
In the same vein, there appear to be - by common usage - new rules. "CD's" meaning several of them, for instance. To me and the chain of Sisters Of Mercy authorized to feed my mind as a child, that's a POSSESSIVE case, as in "The CD's case was left on the floor where my foot found it and skated across the rug like Peggy Flemming in her day." But no, you see a flying apostrophe thrown after many words as if someone got a truckload wholesale, discovered they expire, and is trying to get them out of there before they stink up the place!
I am confused enough already.