Tip: some things you may not know about Facebook groups

As the updated Facebook Groups options make their way to more and more accounts, you might see some things you don't expect. Yes, a Facebook friend can join you to a group they're a member of and you'll show up as a member and start getting messages from the group - and you might never see an invitation message. It all depends on how your Facebook email notifications are set (and maybe whether your account has all the new features); so yes, the rumours of Internet celebrities getting joined to satirical groups that appear to be about dubious subjects are mostly true.

As Facebook puts it in the help page:

"The functionality of approving a group membership is not available. Similar to being tagged in a photo, you can only be added to a group by one of your friends. When a friend adds you to a group, a story in the group (and in News Feed for Open or Closed groups) will indicate that your friend has added you to a group.

Please keep in mind: Only your friends can add you to groups. When a friend adds you to a group, you'll get a notification right away. You can leave a group anytime. To do so, just go to the group page and click "Leave Group" in the right-hand column. Once you leave a group, you can't be added by anyone else unless you explicitly request to be re-added."

When Facebook's Zuckerberg was added to one of these satirical-offensive groups, he left a note that this was why it was so easy to leave a group and unsubscribed. And yes, only friends can add you to a group, so you're safe unless one of your Facebook friends has a nasty sense of humour. UPDATE: Facebook's Justin Shaffer tells us it's not true that if a friend joins you to a group and you leave it, they can't join you to any other groups afterwards. Things may be different if you're Zuckerberg of course...

Still, people are concerned that they'll be added to groups that look offensive and it will spoil their reputation. We can certainly see that happening; we can also see this as a possible trigger to make people evaluate who they 'friend' on Facebook a little more carefully. The bottom line is that yes, yet again Facebook has defaulted to opt-out rather than opt-in (a cynic might suggest that it's hard to work up the same sense of outrage every time a service so ubiquitous that even outspoken Facebook critic Jason Calacanis can't stay off it because he needs an account to sign in to new services, makes the same mistake). At this point our advice remains that as soon as you hear about a new Facebook feature, especially if it's something that Facebook says might improve your privacy, you should go and check all your Facebook settings to see if you need to change anything because Facebook has a rather Hmpty-Dumpty definition of 'improve'...

Assuming you want to be in the group you get joined to, there are a couple of other things you might want to know.

Where are my notifications? If you're on Gmail they're probably in your spam folder. If you're on Hotmail they're nicely classified as social updates. If you already have a filter or a rule for Facebook messages, they're wherever the rule puts them.

Why am I getting notifications for this group I've never heard of? A friend joined you to it and your settings are bringing you the messages - leave the group or change your notification settings.

Do I have to get a notification for every message? Facebook promoted the feature as for small groups; friends, families, clubs- but the first group I was invited to had well over 500 people before I even saw my invitation. Will you get all those messages emailed to you? Depends on what you have set under Account->Account Settings->Notifications; you can get notifications for when anybody posts (think new topics), when anybody posts or comments (that's everything) or only when friends post, or maybe just when people reply to a thread you've commented in. You can change individual group options from the link at the bottom of the Groups Notification settings or use the Edit Notifications button in the top right corner of the page for a specific group.

"The emails are including threading data," Groups manager Justin Shaffer told us, "so they'll work nicely in a client that supports it like Gmail or mail.app etc." Messages thread in Outlook 2010 for example, and although notifications currently include all the comments in a thread in every notification, "that should be fixed with the next release," Shaffer promises.

How do I get back to a thread to comment on it? Don't click the name of the person you want to reply to; that opens their profile. Or their picture. This is changing as Facebook works on the Groups tool and you can now click on the ink at the top of the message that says 'So and so's post'. Or scroll down and click the View on Facebook link at the bottom of the email notification (the bug that stopped this link appearing in email has been fixed, so if you weren't seeing it check a new notification) - and although the notifications don't say so, "you can also just reply to any of these emails now, and that will post a comment to the appropriate thread, just like with status updates," Shaffer told us (and it works nicely).

I've been added to a group I like and I want to bring my friends; can I? Depends; the group can be set up so the owner gets to choose or so any member can add any other friend.

I haven't been added to a group I like... See that 'Ask To Join Group' button on the top right?

How do I see when new people join the group so I know whether I'm still in the cosy, private group I started out in? Watch the stream of posts like a hawk, because there doesn't seem to be an email notification to tell you that. Sure it would get irritating in a big group of hundreds of people (like the opening and slamming door sounds AOL used to have in its instant messenger as people signed on and off; a network outage in the AOL office sounded like a tantrum in a kindergarten), but Facebook keeps telling us groups are for small, select groups of people...

Why is this old conversation at the top of the group page? Because it's the latest conversation with a new comment. Comment on an old conversation and it pops back up to the top.

Why do some of the groups I see have an icon and some are just a link? That's new groups and old groups; you can keep using old groups but once you get the new groups features you can't make any more old groups - and you can't currently convert an old group to a new group..

But what are Facebook groups for? Talking to a group of people who may or may not be in your own social network already; groups is a way to either divide up your current social network for discussions or to talk to people who are friends with your friends. No, we're not quite sure either. M