what are the environment variables,how do you use them. give an example.

Environment Variables are variable whose value is fixed for its usage everywhere.
There are two types.
1.Built in-which are already existing in QTP which we can directly use in out script.
ex:ActionName,ActionIteration
2.User-defined
which user has to define and use those variables anywhere in the action.
Ex:File path-Suppose you are reffering a data file in ur script then store the location of your file path in environment variable and use it across the actions.