Batch : For what is percentage followed by asterisk used?

This is used to forward the parameters you passed in to the batch file to another application.

For example if you call batch.bat param1 param2 param3 param4 and inside your batch.bat file you have Text.exe %*, it will be equivalent as calling Test.exe param1 param2 param3 param4

With that explanation, you can call an executable or other script with the exact same parameters as were passed to this script. So that allows you to easily 'wrap' an executable in a script that does some action before and/or after running the executable, while still supporting all command line parameters the executable supports.