Waterfall model is a simplest and widely used process model for software development. In the waterfall model, project begins with the feasibility analysis. On successfully demonstrating the feasibility of a project, the requirement analysis and project planning begins. The designing starts after completing the design phase. On completing the coding phase, testing is done. On successful completion of testing, the system is installed. After this, the regular operation and maintenance of the system takes place.

The important characteristics of this model are:

• The process software consist of three linear set of distinct phases

• Requirement Analysis

• Project Planning

• System Design

• Detailed Design

• Coding & Unit Testing.  

• System Integration & Testing

• At every phase there is a provision for verification & validation

• This model allows communication between customer and developer