My gid vs. All Groups I Belong to

Question

I am using Debian 8.

Executing id gives this output:

uid=1000(myUserName) gid=1000(myUserName) groups=1000(myUserName),48(sudo)

Is there anything special about a group that's automatically created when a user is created vs. a group that's created with groupadd?

Is the display of "gid=1000(myUserName)" redundant to the display of "groups=1000(myUserName),48(sudo)", or is the display of "gid=1000(myUserName)" meant to convey something to me that the display of "groups=1000(myUserName),48(sudo)" does not?

Answer 1

The part that shows "gid=1000(myUserName)" is showing your primary group.

For any file or directory you create, this group will be the owner.

For every process that you start this will be the owner. (there are exceptions to this rule, but usually it is like that).

The line "groups=1000(myUserName),48(sudo)" shows the groups that you belong to, including your primary group.