 Welcome to the session on the need of SRS document in software development life cycle. At the end of this session students will be able to identify the needs of SRS document. Let us discuss what is the need of SRS documents in software development. SRS that establishes the basis of agreement between the user and the supplier on what the software product will do. It is an agreement between the customer and organization, the organization that is developing a software. So the user needs how to be satisfied but the user may not understand the software. The developers will develop the system but may not know about the problem domain. So SRS document is the medium to bridge the communication gap and specify the user needs in a manner that both can understand. So it is an agreement between the customer and the supplier or the client or the organization. SRS it helps the user to understand his needs. They do not always know their needs. They know the problem, they are find difficult to express the exact requirements or the features of the software or the different functionalities of the software. So they do not always know their needs and must analyze and understand the potentials. So the goal is not just to automate a manual system but also to add a value through it. The software developer role is not just to make an automation of a system but we need to make a quality software. The requirement process that helps to clarify the needs. The SRS document that will help to understand the needs of the user. SRS also provides a reference for validation of a final product. The clear understanding about what is expected or if the software meets the requirement. So it is a validation. Validation means that software should satisfy the SRS needs, means whatever the requirements that are mentioned in a SRS document. So the user needs are satisfied by a software. So SRS document acts like a validation of the requirements. High quality SRS document is essential for high quality software. These errors get manifested in the final software. To satisfy the quality objective, it must begin with high quality SRS document. So the requirement defects are not few. There are some cases are there where 25% of all the defects in one case it is arised at that requirement phase. So out of 25% is the 54% of all the defects are found after the coding and unit testing and that of 45% of these errors are actually originated during the requirement stages. Good SRS reduces the development cost, SRS errors are expensive to fix later. requirement changes can cost a lot up to 40%. Good SRS document can minimize the changes and errors that occurs in the later stages. So substantial savings, the extra effort spent during the requirement saves the multiple times that effort. So let us consider one example. The cost of fixing errors in the requirement phase, design phase, coding phase, acceptance testing phase and operation and maintenance phase are given as 2% per month, 5% per month, 15% per month, 50% and 150% per month as per the phase wise. This is the cost of fixing errors in the each phase. After requirement phase the 65% of the requirement errors are detected in the design, 2% in the coding, 30% in acceptance testing and 3% during the operation. So this is they are given the requirement errors that are detected after the requirement phase. After the requirement phase that comes the design, coding, testing and maintenance phase. So their percentage of errors are given. So in continuation with that input values, if the 50 requirement errors are not removed in the requirement phase, if the 50 requirement errors are not removed in the requirement phase, the total cost is the total cost is. So here there are 65% so 65% so in that if the 50% 50 requirements are not removed in the requirement phase. So what happens here 65 into 50 by 100 so that is 32.5 so 32.5 into 5, 5 means what is the 5 so it is given in the example that in the design phase it is required 5% per month so 32 into 5 into 5. Then next given as a 2% in coding so 2 by 100 into 50 okay 2 into 50 by 100. So we will get 1 so 1 into in the coding phase they are given 15% per month and similarly for similarly for the testing phase 30% so 30 into 50 by 100 so that is 15 into 50 is the person per month. So similarly that we will get 1,152 hours when when if the 50 requirements errors are not removed in the requirement phase if the 50 requirement errors are not removed in the requirement phase then the total cost is 1,152 hours. So it is based upon the the cost of fixing the errors that is given in the example. So if 100% per hours 100% per hours are invested additionally in the requirement phase in the initially only to catch these 50 defects then the development cost could be reduced by 1,152% per hour. So the net net reduction is 1,052% per hours means here we need to find the defects as early as possible so we need to spend more effort in the initial phase only otherwise if there are 50 requirements errors are not removed then the cost will be 1,152 errors because the the the requirement errors the requirement defects that are fixing at the later stages so the cost will be more. Now let us pause the video for a while and just analyze the graph what actually the graph is. So the graph this contains the x axis the different phases of the software development requirement design code testing acceptance operation and as the y axis given the relative cost to fix the errors. So the graph it is increasing with respect to the different phase wise means if we fix the errors at the later stage then the cost of the cost of fixing the defects is increases. Suppose in the requirement phase the cost is very less and suppose if we fix the defects at the later stages at the acceptance test stage then the cost will be more cost will be more. So remove the defects early as the cost of removing defects that increases with the latency. So these are the references I have referred thank you.