LoadRunner consists of several key components:

Virtual User Generator (VuGen): Used to create and edit test scripts by recording user actions.
Controller: Manages and executes load test scenarios by coordinating multiple virtual users and collecting performance data.
Load Generators: Machines that generate virtual users to simulate user load on the system.
Analysis: Provides detailed reports and analysis of the test results to identify performance issues.

To create a test script in LoadRunner using VuGen:

Open VuGen and create a new script by selecting the appropriate protocol (e.g., HTTP/HTML).
Start recording your actions by interacting with the application under test. VuGen records these actions and generates a script.
Stop the recording when you have captured all necessary user interactions.
Edit the generated script to enhance it, including parameterizing inputs, adding transactions, and inserting checkpoints.
Save the script for use in load testing scenarios.

 Parameterization in LoadRunner is the process of replacing hard-coded values in a script with variable data. This is important because it:

Simulates Real User Behavior: Uses different data sets for each virtual user, mimicking real-world usage patterns.
Avoids Caching Issues: Prevents the server from returning cached responses, providing a more accurate measure of performance.
Tests with Varied Data: Allows for testing different input values and scenarios, improving test coverage and identifying potential issues with various data.

After running a load test, you can analyze the results using the LoadRunner Analysis component:

Open the Analysis Tool: Load the results file generated by the Controller.
Review Summary Reports: Look at key metrics such as response times, throughput, hits per second, and error rates.
Examine Detailed Graphs: Use various graphs to visualize performance data over time, identifying trends and anomalies.
Identify Bottlenecks: Look for points where performance degrades, such as high response times or resource utilization.
Generate Reports: Create comprehensive reports to document findings and share with stakeholders for further investigation and optimization.

LoadRunner is used for performance testing applications by simulating user activity and measuring system behavior under load.

VuGen (Virtual User Generator) is used to create and edit test scripts by recording user actions.

Use the Controller component to manage and execute load test scenarios.

A Load Generator is a machine that simulates virtual users to generate load on the system.

Use the Analysis component to review performance metrics and identify bottlenecks from test results.