Classify Testing Activities by Stage

(1) Programmers write tests for individual methods as they develop code,Development Testing

(2) A customer runs the system using their own data to decide if it should be accepted,User Testing

(3) A separate testing team validates a complete system version before it is shipped,Release Testing

(4) A selected group of users experiment with an early release to find issues,User Testing

Explanation

Development testing is done by programmers during development. Release testing is done by a separate team on a complete system before release. User testing involves actual users - including both alpha/beta testing (selected users experimenting with releases) and acceptance testing (customers testing with their own data).