Every file in Linux is owned by a specific user and a specific group. To demonstrate, let's switch to user smurf, and create a file named mysmurf in smurf's home directory:
root@ubuntu-linux:~# su - smurf
smurf@ubuntu-linux:~$ touch mysmurf
Now do a long listing on the file mysmurf:
Figure 4: User and group owners
You will see the name of the user (the user owner) who owns the file in the third column of the output, which is, by default, the user who created the file.
On the fourth column of the output, you will see the name of the group (the group owner) of the file, which is, by default, the primary group of the user owner.
The developers group is the primary group of user smurf, and hence developers became the group owner of the file mysmurf.
If you do a long listing on the sports directory that's inside elliot's home directory:
smurf@ubuntu-linux:~$ ls -ld /home/elliot/sports
drwxr-xr-x 2 elliot elliot 4096 Oct 22 12:56 /home/elliot...
