What Is Requirement ?

A capability that the system must deliver
A capability needed by the user to solve a problem to achieve an objective

What requirement Are Not ?

project planning information
design or implementation details or
testing information

Why Requirement Analysis ?
The earlier in the cycle the defect is corrected
Cost
Delay
Profit
Customer satisfaction
Customer confidence

Type of Requirement 
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Business Requirement :</div><div class="text_exposed_show">
Business requirements represent a kind of “why” information. It represent the high level of objectives of the organization or customer who requests the system. Business requirement why the organization is implementing the system. Vision and Scope statement record the business requirement. </div><div class="text_exposed_show">
User Requirement :
requirements constitute one type of “what” information. User requirements describe what the user will be able to do with the product, such as goals or tasks that users must be able to perform. Use cases, scenarios, user stories, and event response tables are some ways to represent user requirements.</div><div class="text_exposed_show">
Functional Requirement </div><div class="text_exposed_show">Functional requirement specify the software functionality that the developer must build into the product to enable the user to accomplish their business requirement . Functional requirements represent one kind of “what” information. The traditional “shall” statements that describe what the system “shall do” or what the system “shall let the user do.“
</div><div class="text_exposed_show">System Requirement
Describe the top level requirement for a product that contain multiple subsystem that is a system. A system can be all software or it can be both software and hardware.</div><div class="text_exposed_show"></div></div></div></div><div class="UIImageBlock clearfix mentionsAddComment"><div class="commentArea UIImageBlock_Content UIImageBlock_ICON_Content"> </div></div><div class="clearfix insightsBar"><div class="rfloat"></div></div>