> For the complete documentation index, see [llms.txt](https://qatesting.gitbook.io/qa/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://qatesting.gitbook.io/qa/manual-testing/sdlc/phase-5-testing.md).

# Phase 5: Testing

The testing phase of the Software Development Life Cycle (SDLC) is where the software system is tested to <mark style="background-color:yellow;">**ensure that it meets the requirements and quality standards set by the customer.**</mark> This phase is <mark style="background-color:red;">**critical**</mark>, as it ensures that the software system is stable, reliable, and functional.

## Testing Phase Activities

* Unit Testing: This involves testing individual software components or modules to ensure that they behave as expected. Unit testing is typically carried out by developers.
* Integration Testing: This involves testing the interfaces between the various software components and modules to ensure that they work together as expected. Integration testing is typically carried out by developers.
* System Testing: This involves testing the entire software system to ensure that it meets the requirements and quality standards set by the customer. System testing is typically carried out by independent testers.
* Acceptance Testing: This involves testing the software system with real-world data and scenarios to ensure that it meets the needs of the customer. Acceptance testing is typically carried out by the customer.

{% hint style="success" %}
The output of the testing phase is a <mark style="background-color:purple;">**fully tested software system**</mark> that <mark style="background-color:orange;">**meets the requirements and quality standards set by the customer**</mark>. This system includes all the software components and modules, database structures, and user interface, and has been integrated into a cohesive system.
{% endhint %}