What is tested during acceptance testing?

Acceptance testing verifies whether the finished product or its functional part meets the business and customer requirements. The main goal is to ensure that the system is ready for release and use by end users.

The following are tested:

Compliance with business requirements: Verification of the implementation of all functions and flows stated in the non-functional requirements from the perspective of the end user or business representative.
Operational effectiveness of key usage scenarios: Testing the main user paths in the system that are critical for performing business tasks.
Compatibility: Including compatibility with different browsers (cross-browser testing), operating systems, devices, or their combinations, if specified in the requirements.
Performance (at a basic level): Evaluation of system responsiveness and speed of executing key operations under expected load.
Usability: Checking the intuitiveness of the interface, ease of task completion, and overall user experience, and how well it meets expectations.
Localization and internationalization (if necessary): Verification of correct display and functioning of the system in different languages and for various regional settings.
Security (at a basic level): Verification of the correct operation of authentication and authorization mechanisms, and the absence of obvious vulnerabilities.
Data integrity: Verification of the correctness of data saving, retrieval, and processing according to business logic.

It is important to note that acceptance testing is often conducted by business representatives (User Acceptance Testing, UAT) or a dedicated group of end users to confirm that the solution meets their expectations and is ready for "acceptance".