1. Functionality: the degree to which the functions realized by the software meet the needs of users. Functionality reflects the degree to which the developed software meets the user's explicit or implied needs, that is, whether all the functions required by the user have been realized.

2. Reliability: the degree to which the software can maintain its performance level under the specified time and conditions. Reliability is an important quality requirement of some software, which not only reflects the degree to which the software can meet the needs of users and run normally, but also reflects the degree to which the software can continue to run when there is a fault.

3. Ease of use: For a software, the degree of efforts made by users in learning, operating, preparing for input and understanding output. Ease of use reflects the friendliness with users, that is, whether it is convenient for users to use this software.

4. Efficiency: the effectiveness of computer resources (including time) needed to realize a certain function with software under specified conditions. Efficiency reflects whether there is a waste of resources except "resources" when completing functional requirements; This term has a wide range of meanings, including the use of internal memory and external memory, channel capacity and processing time.