This information is listed on user webpages, which you can locate by typing a username into the search bar or using, for instance, the Active Directory Users OU widget. You can also run custom reports. A sample report can be seen below.
Select Top 1000000 tblADusers.Username,
tblADusers.Userdomain,
tblADusers.Firstname,
tblADusers.Lastname,
tblADusers.Name,
tblADusers.Displayname,
tblADusers.OU,
tblADusers.Lastchanged,
tblADGroups.Name As [Group],
tblADGroups.Description As GroupDescription
From tblADGroups
Inner Join tblADMembership On tblADMembership.ParentAdObjectID =
tblADGroups.ADObjectID
Inner Join tblADusers On tblADMembership.ChildAdObjectID =
tblADusers.ADObjectID
Order By tblADusers.Userdomain,
tblADusers.Username,
[Group]