Java Security Manager
This implements the overall security strategy and is completely customizable by those authorized. Thus browsers can implement a particular Security Manager but as mentioned Applets cannot!
In particular the Security Manager implements the differences between Java Applets (no local file operations etc.) and Applications
- Note you can download a Java Application that has NO Security Manager restrictions!
In general Security Manager controls thread access, OS access, network access and other Java class access.
It controls installation of Class Loaders
It (will) process encryption based authentication mechanisms