How load runner works?

Suppose you want to test a bank server that serves many automatic teller machines (ATMs).

The ATMs provide a full range of banking services to the bank's customers--such as withdrawing and depositing cash. 

To test the bank server using LoadRunner, you create a scenario. The scenario defines the actions that are performed on the server during the load test. During the scenario that loads and monitors the bank server, you want to:

1. emulate conditions of controlled load on the server
2. emulate conditions of maximum load on the server
3. measure server performance under load
4. check where performance delays occur: network or client delays, CPU performance, I/O delays, database locking, or other issues at the server monitor the network and server resources under load