Java is a programming language first released by Sun Microsystems in 1995. There are many applications and websites that will not work properly unless you have Java installed so chances are you already have it installed. The problem lies in which version or versions are installed on your computer.
First, and most importantly, when you get a pop-up telling you that an update it available for Java, click OK to allow it. Updates are very often security updates, meaning they have found a vulnerability in the program and are fixing it with an update.
Next, go to Control Panel then Programs (or Add/Remove Programs) to uninstall old versions of Java. There should only be one version installed; it will be Java 7 Version 25 or higher if it is “up to date”.
If you have Java 6, uninstall it; there may be multiple versions of Java 6. Uninstall them all. This is very important! Starting with Java 7, old versions will be uninstalled when an update is applied but Java 6 must be uninstalled manually.
Visit Java’s website to remove older versions.
UPDATE: Java is so vulnerable and incessantly updating, I have since revised my policy and now simply uninstall Java. The only folks who seem to need it are those that play online games and don’t get me started on that risky behavior.