Twitter have recently added a new 'Lists' feature which is a new way to organise people you’re following on Twitter, or find new people. In other words a groups feature.

Twitter List’s are really easy to create and manage. Simply login to your twitter account and click 'Create new list' on the top left.

First, you’ll be asked to provide a name for your list (i.e. friends, co-workers, family).
The name is also used for your list’s URL, which will be 'twitter.com/username/list-name'. You’ll also be asked if you want your list to be public or private.

Public Lists – These lists can be seen by anyone, and anyone can follow them.
Public lists are ideal for lists of recommended follows.

Private Lists – When Twitter says private, they mean private. Only the creator of private lists will be able to see or subscribe to them — not even those on the list can see private lists. That means, for example, you could create a list of your competitors and keep an eye on them without them being any the wiser.

Once you’ve clicked the 'Create list' button, you’re ready to add users.
After you create a new list, you’ll be prompted to search for people to add to your list, but there are really two ways to add users to lists. First, you can add users from their profile page, by clicking the lists button and checking off the lists you want to add them to from the drop down menu. You can add a single user to multiple lists.

Checkout Ph.Creative’s TEAM list!
http://twitter.com/phcreative/team