The Twitter team finally made list functionality available to everyone. Hooray!
What can you do with lists?
1. Lists can be created:

Preset.

2. You can add users to the lists:

')
or so

3. You can follow the lists in the same way as individual users:

get here

On the official blog of developers yet nothing is said about it.
ps: it may well be that I did not consider all the functionality of the groups, so additions in the comments are welcome;)
UPD: in the comments suggest that the lists, all the same, are not yet available to everyone.
UPD2: I was asked to add an article with a description of how lists can be used.
In the comments habr-user
iSlava gave a link to a note in his blog, where one of the ways of application is described at the end. Namely for the weekly followFriday.
Personally, I have been using groups for a long time through the desktop client for Twi - TweetDeck. There, too, there are groups that are absolutely similar in functionality.
Of course the main goal of groups is to separate some people from others. By interests, topics, etc. Next, we select the desired group and read that set of twitter that we are interested in at the moment.
I have two groups. In the first there are people whose tweets I read everything. Those. these are the most interesting people / organizations for me. In the second group - all the rest. I sometimes glimpse their tweets for something interesting.
Such groups can be created as much as you like. For example:
- Your employees
- Your friends
- Family
- Fellow students
- A group in which twitter only financial organizations
etc. Here you can fantasize to infinity.
It may well be that there are other ways to use groups and someone will tell about them in the comments. ;)