To say which part of the software development process is most important is almost like asking which of a car's four tires is most important. Clearly, all elements involved in software development are necessary and critical to its success. However, if forced to select one that I consider most important, that one would have to be the requirements phase. As the building block of the entire process identifying the requirements and then setting the scope of the development process through those requirements is key to the success of a project. If the requirements are improperly defined or identified, then it will not matter whether the design, the coding, or the testing phase proceed perfectly because the project will not do what it is expected to do nor what the customer wants it to do.