What is the difference between a cohort and a group?
See #1.2 in Groups FAQ
I created a cohort and now I can't find it again!
If you create a cohort from Administration>Site administration>Users>Accounts>Cohorts and then assign it to a category, you will not see it listed on that screen. To view or edit it, you need to go to the category page and click the Cohorts link in the Administration block there:
Can I synch cohorts with LDAP groups?
This is not currently available as standard. However, the tracker issue for this - MDL-25011- offers a patch which works on versions up to and including 2.3. It has not yet been tested on 2.4.
Where can I practise with some ready made cohorts?
I want to enrol a cohort of students into a category
This is not currently possible. Please see MDL-36951 for the reasoning behind this.