Java Virtual Machine is the name that Java Runtime Environment was known for a time.
There are plenty of websites that make use of Java technology to enrich the experience of visitors; from banks websites, to video games webpages, all of them require Java to function properly.
Formerly was known as Java Virtual Machine (JVM), the program required to run web pages that made use of Java. At present the JVM is known as JRE (Java Runtime Environment) and can be installed on Windows, Mac and Linux.
With JRE (Java Runtime Environment) as well as be able to view web pages that make use of Java, you can run all those applications that have been developed in the Java programming language and that have extension .jar.
Once you have installed the JRE, the program will take care of updating automatically and this way we will always have the latest version. There is the chance that your computer already come with the pre-installed JRE, so if it is a very old version, we may have to uninstall it by hand to subsequently install the latest version.
JRE is virtually indispensable in all computers, because sooner or later we will use a program or website that you use Java and therefore requires us to have Java Runtime Environment installed.