A POLICY file is a configuration file used by Java Runtime Environment (JRE) and Java SE Development Kit (JDK) to determine the granted permissions for each Java program. It contains a list of permission information that specifies the types of system resource accesses that can be used by a Java program.

Java Virtual Machine (JVM) enables a computer to run a Java program. JRE is a software package that includes a JVM implementation and a Java Class Library implementation. JDK is a superset of JRE and also comes with Java programming tools. POLICY files are used by JRE and JDK to determine the permissions of Java programs installed on the computer. The file grants access to actions such as read/write permissions to files in a certain directory. You can create and edit POLICY files with a text editor or the policytool utility, which can be opened by typing policytool at the command line in the JDK. If a POLICY file is updated the Java programs must be restarted in order for the updates to be applied. If there any syntax errors in the POLICY file the Java programs will fail. Using the policytool utility will help prevent syntax errors. There are 2 POLICY files by default, one is a system-wide POLICY file and the other is a user POLICY file. The location of default system-wide POLICY files: Windows: java.home\lib\security\ macOS/Linux: java.home/lib/security/ The location of default user POLICY files (user.home is the user's home directory): Windows: user.home\.java.policy macOS/Linux: user.home/.java.policy