why don't we just debate abortion while we're at it

yea, apostrophe could certainly be used there..

"O baby.."

hmm

you seem very angry about this alec. maybe you should take a lie down

To me, the really grating thing is how you need to change people's names sometimes, like in "the Williamses' house". It just seems very wrong to change an identifier as important as a personal name like it's just another malleable word.

i don't know if someone responded already, but this is wrong. if a family's last name is "Williams", you would pluralize it as either Williams' or Williams's (although they could both be PRONOUNCED as "Williamses"). "Chris's pants" and "Chris' pants" are both correct in all situations (it's a regional usage issue)

i think most people here seem to understand that apostrophes are correctly used for both contractions and possessives, with "its" (possessive) being an exception. however something that a lot of people get confused about is plural possessives and exception words. here is an example situation:
there are multiple carpenters working with multiple wrenches-- "the carpenters' wrenches". there is only one carpenter working with multiple wrenches-- "the carpenter's wrenches". there are multiple carpenters working with one wrench-- "the carpenters' wrench". there is only one carpenter working with one wrench-- "the carpenter's wrench".
(exception to the above rule: always use children's, never childrens'. another example of this is "women's rights".)
so basically, horse's and horses' are both correct but in different situations. you can't say "the horses' hooves" when you're only talking about ONE horse.

i love grammar and i know a lot about it, but i do purposely defy certain rules because i think they should be changed. even though i don't always put my commas inside the quotation marks, i still know that that is what is "correct". however, i think that the rules for using apostrophes are pretty reasonable.
let's turn this into a grammar thread! i want to talk about commas and semicolons and stuff...
p.s. i recommend that everyone read the book "Eats, Shoots and Leaves" (although keep in mind that it follows British grammar so not all things apply to American grammar that many of us are used to)

never childrens'

this is WRONG. I had to learn it the hard way. Ynd I know, 'how can it be wrong, children is already in plural form, there must not be an 's' in it.'
Actually, words like those could still be pluralized (oooohhhhh). When you say 'childrens' it means many children, as opposed to many child. It means you take the 'children'  as a singular entitiy and pluralize it. Kinda like when you take a group, not as a group of person but as a 'group' <-singular.
Childrens means you have many 'children', meaning you have a set of sets of children which are distinct with each other. Now this all boils down to context, but what I'm saying is, that it's nused and it's grammatically correct.

this is WRONG. I had to learn it the hard way. Ynd I know, 'how can it be wrong, children is already in plural form, there must not be an 's' in it.'
Actually, words like those could still be pluralized (oooohhhhh). When you say 'childrens' it means many children, as opposed to many child. It means you take the 'children'  as a singular entitiy and pluralize it. Kinda like when you take a group, not as a group of person but as a 'group' <-singular.
Childrens means you have many 'children', meaning you have a set of sets of children which are distinct with each other. Now this all boils down to context, but what I'm saying is, that it's nused and it's grammatically correct.

hmm i don't know about that. yes it is all about usage, but i don't think that situation is correct, and i can't find anything online or in my grammar books that suggests it.
i know it's correct to say peoples' (possessive apostrophe) though, but that's because the word peoples is a plural of a plural-- example: "various peoples moved into the nation", where peoples is referring to multiple sets of people. childrens is not a plural (of a plural) in any case, not even when referring to multiple sets of children. so adding an apostrophe after it would never be correct. children's can still refer to multiple sets of children.

language is changing. there is no magic standard. either you follow one style manual or you follow a different one. written language doesn't even really correspond properly to how we talk. it's good to be consistent up to a point (most of the time). after that point is reached and people break into debates, it becomes a waste of time because there is no right answer. in my opinion, the best solution is to look up some weirdo's rulebook like The Elements of Style or some other thicker style manual and do whatever they say to do. some universities and organisations even have preferred style manuals iirc.

the most important rule of written language is DO NOT CAPITALISE ANY LETTERS. do not forget this now that i have told it to you.

is it capitalise or capitalize?

I was taught it wrong too.