User and Group
User
Checking your username
whoami
List all users logged into the server
who
Groups
Groups in Unix systems are used for multiple purposes, including controlling access to files and directories, and limiting executing of some binaries. A user could be assigned to multiple groups.
In HPC clusters, groups are also used to grant accesses to a specific partition on Slurm, which is the job management software.
Listing groups an user is assigned to.
groups <username>