What is the use of Environment variables in QTP?

What is the use of Environment variables in QTP?

QuickTest can insert a value from the Environment variable list, which is a list of variables and corresponding values that can be accessed from your test. Throughout the test run, the value of an environment variable remains the same, regardless of the number of iterations, unless you change the value of the variable programmatically in your script.

Tip: Environment parameters are especially useful for localization testing, when you want to test an application where the user interface strings change, depending on the selected language. Environment parameters can be used for testing the same application on different browsers.