Prototype Model: show a simple sample early
Build a working prototype of the system before developing the actual software. The prototype has limited functional capabilities, and its performance might not be optimal compared to the actual software. Seeing it makes it easier for customers to understand what they want, and helps developers understand how to build it better once they have done it the first time. The prototype is usually not used later — it is thrown away and new software is built.
Advantages: useful when the exact form of the solution and technical issues are unclear; useful to get feedback from customers.
Disadvantages: increased development cost (prototypes usually aren't reused); since we are not building the actual system, risks and bugs that appear later in the development cycle are not captured.
The prototype model belongs to the Plan and Document perspective.
REMEMBER A prototype is a small working sample for early feedback, not the full product.