The Incremental model combines elements of the linear sequential model with the iterative philosophy of the prototyping. This model has been explicitly designed to accommodate a product that evolves over time.

When an incremental model is used, the first increment is often a core product. The core product is used by the customer or undergoes a detailed review. As a result of use and/or evaluation a plan is developed for the next increment. The plan addresses the modification to the core product to better meet the needs of the customer and delivery of additional features and functionality. Software is constructed in a step-by-step manner. While a software product is being developed, each step adds to what has already been completed.

Advantages of Incremental Model

• System is developed and delivered in increments after establishing an overall architecture.
• Requirements and specifications for each increment may be developed.
• Users may experiment with delivered increments while others are being developed.
• Intended to combine some of the advantages of prototyping but with a more manageable process and better system structure.
• Incremental development is especially useful when staffing us unavailable for a complete implementation by the business deadline.
• Early increments can be implemented with fewer people.

When you encounter a difficult deadline that cannot be changed the incremental model is a good paradigm to consider.