Evaluation is the process of examining a multimedia product to determine what's working, what's not working, and why.
It tests whether a multimedia product fulfils the user requirements and suggests necessary improvements to make the product useful for its target audience.
Formative evaluation is done as a continuous process in the development of a multimedia product. It is a method for evaluating the worth of a program while the program is being developed.
A summative evaluation is a method of judging the worth of a multimedia product at the end of the product design (summation). The focus is on the outcome.