What is a function to capture dynamic values in the web vuser script?

Web_reg_save_param function saves dynamic data information to a parameter.

1. What are the three sections of a Vuser script and what is the purpose of each one?
1) Vuser_init - used for recording the logon.
2) Actions - used for recording the business process.
3) Vuser_end - used for recording the logoff.

2. For what purpose are Vusers created?
Vusers are created to emulate real users acting on the server for the purpose of load testing.