1. User Requirements:
The user requirement(s) document (URD) or user requirement(s) specification is a document usually used in software engineering that specifies what the user expects the software to be able to do.
Once the required information is completely gathered it is documented in a URD, which is meant to spell out exactly what the software must do and becomes part of the contractual agreement. A customer cannot demand features not in the URD, while the developer cannot claim the product is ready if it does not meet an item of the URD.
The URD can be used as a guide to planning cost, timetables, milestones, testing, etc. The explicit nature of the URD allows customers to show it to various stakeholders to make sure all necessary features are described.

2. User Requirements Functional requirements Non-functional requirements
Describe how the system works.
It specifies something the system should do.
A functional requirement for a milk carton would be “ability to contain fluid without leaking”.
Describe what the system should do.
Specifies how the system should behave.
Non-functional requirements cover all the remaining requirements which are not covered by the functional requirements.
A non-functional requirement for a hard hat might be
“must not break under pressure of less than 10,000 PSI”

3. Functional requirements Non-functional requirements
Functional requirements
Non-functional requirements
Some of the more typical functional requirements include:
Business Rules
Transaction corrections, adjustments and cancellations
Administrative functions
Authentication
Authorization levels
Audit Tracking
External Interfaces
Certification Requirements
Reporting Requirements
Historical Data
Legal or Regulatory Requirements
Some typical non-functional requirements are:
Performance – for example Response Time, Throughput, Utilization, Static Volumetric
Scalability
Capacity
Availability
Reliability
Recoverability
Maintainability
Serviceability
Security
Regulatory
Manageability
Environmental
Data Integrity
Usability
Interoperability

4. Data Types What is it? Can exist in a variety of forms:
Data is distinct pieces of information, usually formatted in a special way.
All software is divided into two general categories: data and programs.
Programs are collections of instructions for manipulating data.
As numbers or text on pieces of paper
As bits and bytes stored in electronic memory
As facts stored in a person’s mind