Functional testing is noting but testing the functionality of the application like testing the each and every component independently and thoroughly with respective to the given requirement it is known as functional testing.
In functional testing we have different testing's they are as follows. UNIT TESTING, INTEGRATION TESTING, SYSTEM TESTING, REGRESSION TESTING.
NON-functional testing is used to test the performance of the application by applying load on the app to test how well the app is working under different conditions.

Functional Testing vs. Non-Functional Testing: Unveiling the Distinctions

1. Functional Testing Functional testing focuses on verifying whether the software application’s functionality aligns with the specified requirements. Here are the key aspects:

Objective: Validate individual components, features, and interactions.
Types of Functional Testing:
Unit Testing: Tests individual units (e.g., functions, methods) in isolation.
Integration Testing: Verifies interactions between different units or modules.
System Testing: Ensures the entire system works as expected.
Regression Testing: Validates that new changes don’t break existing functionality.
Example: Amazon Functional Testing
Unit Testing: Verify that adding a mobile phone to the cart works correctly.
Integration Testing: Ensure that selecting a mobile phone and adding it to the cart integrates seamlessly.
System Testing: Confirm that all features (e.g., search, checkout, recommendations) function properly.
Regression Testing: Validate that existing features (e.g., payment, order history) remain unaffected.

1. Non-Functional Testing Non-functional testing assesses aspects beyond functionality, focusing on performance, usability, and other quality attributes. Key points:

Objective: Evaluate how well the application performs under various conditions.
Types of Non-Functional Testing:
Performance Testing: Measures response time, scalability, and resource usage.
Load Testing: Assesses system behavior under heavy user loads (e.g., 100,000 users).
Usability Testing: Evaluates user-friendliness, navigation, and overall user experience.
Security Testing: Checks for vulnerabilities and unauthorized access.
Compatibility Testing: Ensures compatibility across browsers, devices, and platforms.
Example: Load Testing for Amazon
Scenario: Simulate 100,000 concurrent users accessing Amazon.
Objective: Verify that the app remains responsive and stable.
Metrics: Measure response time, server load, and resource utilization.
Outcome: Ensure the app can handle the load without crashing or slowing down significantly.