Difference between JRE and Java Plugin
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I read here
http://www.oracle.com/technetwork/java/index-141825.html
JRE 1.4 (includes Java Plug-in 1.4)

What's difference between JRE and Plug-in ? What's the use of plugin ? Is it used by Firefox and Chrome ? 

When installing Chrome will it install Plug-in itself ? If yes what if Google Chrome install a plugin version and the JRE version is lower ?