There were a flurry of updates to Java version 7 since Homeland Security and other entities declared Java a significant security risk. Questions were raised whether or not Java could be successfully patched, at least in a reasonable amount of time.
Now the updates had settled down quite a bit since Update 21 and has been holding at 25 for, oh, say a month or two.
If you took the stormy clouds of threatening warnings to heart or head and turned off or uninstalled Java entirely - and find that you still don't need it, then do nothing.
But if you haven't turned off or uninstalled Java, here's the link to check whether your version is up to date: http://java.com/en/download/installed.jsp
When done, your browser should show the following confirmation:
Safe surfing, now!