Why are there many tmpfs filesystems mounted on the server?

Issue

• Why are there many tmpfs on the system which are not in /etc/fstab file?
• What is the purpose of having these tmpfs mounted?

Filesystem Size Used Avail Use% Mounted on
tmpfs      187G    0  187G   0% /dev/shm
tmpfs      187G  41M  187G   1%  /run
tmpfs      187G    0  187G   0% /sys/fs/cgroup
tmpfs       38G    0   38G   0% /run/user/1710
tmpfs       38G    0   38G   0% /run/user/900
tmpfs       38G    0   38G   0% /run/user/1708
tmpfs       38G    0   38G   0% /run/user/0