Why Requirement Analysis and it's types?

Why Requirement Analysis and it’s types?
                                                                                             
To develop quality software – on time and on budget – that meets customers’ real needs. Project success depends on good RAM.The earlier in the cycle the defect is corrected
-Cost
-Delay
+Profit
+Customer satisfaction
Cuddling customer confidence

Business Requirement
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.

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.

Functional Requirement
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.“

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.