What type of testing is done only once during the software development cycle to check the software?

Final testing, often referred to as acceptance testing, is conducted once, typically at the end of the software development cycle, to ensure that the system meets the specified requirements and is ready for deployment to users. This type of testing is critical as it acts as the last line of defense before the software is released, confirming that all systems are functional and that it behaves as expected in a real-world scenario.

During final testing, various factors are assessed, such as usability, performance, and compliance with specifications. This is different from other testing types like unit testing, which focuses on individual components, integration testing, which tests combined parts, and alpha testing, which is an early testing phase involving internal users. Each of these testing types is performed at different stages and with different goals, making final testing unique in its singular occurrence towards the end of the development cycle.