Sometimes, what's not said on your wedding invitations is as important as what is said. Yes, you need your guests to know when and where you're getting married, as well as who is hosting, but other things are better left unsaid. Your invites and stationery are still very much tied to etiquette customs and traditions, and as such, should abide by those proper rules. Here, some information that should never be included on or placed inside a wedding invitation:
Registry or gift information: Although a wedding invitation requires a gift in return, it is in extremely poor taste to insert a "helpful" list of places where the bride and groom are registered or a checklist of the things they want or don't want. This information should be shared with parents and attendants who can be resources for guests who want to know. The wedding website is also a perfectly appropriate place to share this information.
The inclusion of "No Children:" Never print "No children" or "Adults only" on an invitation. The way an invitation is addressed, whether on the outer or inner envelope, indicates exactly who is — and by omission who is not — invited to the wedding.
Alcohol information: It is unnecessary to put "Alcohol Free" or "Wine and Beer Only" on the invitation. Surely this information will not be the deciding factor as to whether or not guests attend. You are inviting them to a wedding, not a cocktail party.