Business requirements, user requirements, functional requirements, non-functional requirements

Software requirements include 3 different tiers-business requirements, user requirements, and functional requirements. In addition, each system also has a variety of non-functional requirements.
Business requirement represents a high-level goal for an organization or customer. Business requirements usually come from the project investor, the customer who buys the product, the manager of the actual user, the marketing department, or the Product Planning department. Business requirements describe why an organization is developing a system, the goal that the organization wants to achieve.  use the foreground and scope documentation to document your business needs, which are sometimes referred to as project outlines or market requirements (project charter or Marketplace requirement) documents. User requirement describes the user's goals or the tasks that the user requires the system to accomplish. Use cases, scenario descriptions, and events-response tables are an effective way to express user needs.  This means that user requirements describe what users can do with the system. Functional requirements (functional requirement) Specify the software features that developers must implement in the product that users use to complete tasks and meet business needs . Functional requirements are sometimes referred to as behavioral requirements (behavīoral requirement) because they are traditionally described as "should": "The system should send an e-mail notifying the user that they have accepted their reservation."  Functional Requirements Description is what developers need to implement. System requirement is used to describe top-level requirements for products (i.e. systems) that contain multiple subsystems. The system can contain only software systems, or it can contain both software and hardware subsystems. People can also be part of a system, so some system functions may have to be borne by people.