Open a terminal or command prompt
Type `java -version`
Press Enter
Check the version shown in the output
To check the compiler version, type `javac -version`
Press Enter
Check the version shown in the output
On Windows, you can also open Command Prompt and run `where java`
On macOS or Linux, you can also run `which java`
If multiple Java versions are installed, check the active one with `echo $JAVA_HOME` on macOS or Linux
On Windows, check the `JAVA_HOME` environment variable in System Properties