[ubuntu] 12.04 LTS to 12.04.3 LTS update.

I'm a relative newcomer to ubuntu but have been happily using
version 12.04 LTS for sometime now. Looking at distrowatch I see
that the latest version is now 12.04.3 LTS.

Does the regular update cycle update to the latest version or do
I need to take action? Either updating by the terminal, if yes,
would somebody be so kind as to explain the commands needed
or do I need to download the 12.04.3 iso and install it over the
current version?

System settings > details still shows "ubuntu 12.04 LTS" and system
"up to date".