Hi Everyone!
 
     With the recent controversy about the spelling of grandparents day, I am wondering if there is any place to check other spellings for holiday terms-specifically Happy Holidays or Happy Holiday's--Seasons Greetings or Season's Greetings. I have seen and recieved cards over the years with both spellings, but before I start making holiday cards, I'd like to get it right!  Thanks for your help. cat

Rita is correct.  
 
The best way to determine this is - plural means no apostrophe, possessive means apostrophe.  
 
Sometimes these get tricky, as with a plural possessive (one cat = cat's whiskers/two cats = cats' whiskers).
 
Our beloved English is a minefield of rules and exceptions.  The internet has wonderful resources for rules, and I use it a lot.  Always have to double-think its (possessive without the apostrophe) and it's (contraction for "it is").  Easy for me to screw up.

Although there are too many sites to count, a good, basic one is:
http://www.grammarbook.com/english_rules.asp
 
I have it bookmarked

Thanks Carol-(sorry I confused you  and rita with the request for the site! I will bookmark it also. Thanks Doreen, Although I did check the wiki  before posting, I didn't see the words I was requesting. Thank you all again and have a great day!