What Are Requirements?

For purposes of this class, we will focus on what the end user needs or

expects the system to do. These needs and expectations are documented

as requirements for the system. They fall into two general categories:

user requirements (sometimes referred to as functional requirements) and

system performance requirements (sometimes referred to non‐functional


1. User Requirements describe the tasks the user needs the system to

perform, such as:

• What data the system is expected to collect.

• What the system is expected to do with the data that is input.

• What the system is expected to provide as output (reports, results,


Some example user requirements for an online shopping site might be:

• The system must calculate the total of all items in the online or

website shopping cart.

• The system must display to the user similar items that the online

shopper may be interested in.

Learning Resource


1 of 5 2/7/2023, 5:35 PM

• The system must require the user to provide a shipping address.

• The system must automatically fill in the State portion of the

shipping address based on the zip code entered by the user.

• The system must provide the user with a report of all purchases

made via the website.

2. System Performance Requirements are sometimes referred to

as system quality attributes, since they define how the system is

designed, how it will perform when used, and what the user experience

will be (Microsoft, 2009).

They describe how the system will perform, or its quality, in areas such as:

• Usability—The ability for new users to quickly adapt to the software,

including how easy the system is to use and how help is provided for

the users

• Scalability—The ability of the system to accommodate additional

users and/or additional records/transactions

• Availability—The amount or periods of time the system is to be

operational and useable

• Reliability—The ability of the system to create and maintain the data


• Maintainability—The ability of the system to be easily maintained,

corrected and updated

• Performance—The ability of the system to meet time or volume

requirements (respond to user inquiry, update a database, or handle

the workload)

• Portability—The ability of the system to run/operate on a variety of

end‐user devices or with multiple operating systems

• Interoperability—The ability of the system to interact with other

existing or legacy systems


2 of 5 2/7/2023, 5:35 PM

System performance requirements also describe security requirements for

the system and data, such as:

• Protection of the system from malicious or accidental actions

• Protection of data as it is transmitted and when it is stored

• User authentication; prevention of unauthorized access

• Authorization of users to perform specific functions; prevention of

unauthorized changes to data

• Data backup and recovery

Some examples of system performance requirements are:

• The system must encrypt the user's payment information when it is


• The system must require a retinal scan for login purposes.

• The system must be capable of handling 5,000,000 transactions per


• The system must operate using Motorola handheld scanners.

• The system must be able to accept financial data directly from the

company’s financial system.

To differentiate between user and system performance requirements, the

business analyst determines whether each requirement describes a task

that the system must perform (user requirement) or describes system

quality or security (system performance requirement).

How Are the Requirements Used?

Requirements can be used to develop a system from scratch, in which

case many detailed requirements for every step of every process need to

be clearly laid out. For example, if an accounting system is to be


3 of 5 2/7/2023, 5:35 PM

developed, the developers will need to incorporate all the financial and

legal aspects of the process. They will need to know exactly how each

accounting function is to be performed in order to program the system to

carry out the function.

However, if the intent is to acquire a commercial off‐the‐shelf (COTS)

accounting system or to use a software‐as‐a‐service (SaaS) system, then

the requirements may be stated at a much higher level, such as: "the

system must implement the Generally Accepted Accounting Principles

(GAAP)" or "the system must produce a monthly expense statement." In

these cases, the end user is not so concerned about each step in

performing those functions, as long as the system provides them.

Once the requirements are listed, they can be used to:

• Develop a system and test it to be sure it meets the requirements

• Identify one or more COTS or SaaS systems that appear to meet the


• Test the COTS or SaaS systems to determine which one meets the

most requirements and select one for use

• Identify requirements that are not met that may need be added to

the system or may require a separate or additional system(s) or

processes to be implemented

According to Mitre (2018) requirements "can be tested, verified, and/or

validated, and are unique, complete, unambiguous, consistent, and

obtainable, and [can be traced] to original business and mission needs."

Documented requirements can be traced through an entire system

development and implementation process. For example:

• They form the need for a system and define its scope (all the

functions that are to be included).

• They form the basis for estimating the time and cost of developing or


4 of 5 2/7/2023, 5:35 PM

acquiring the system.

• They are used to develop the system.

• They are used to negotiate any requirements changes that are

proposed by helping to determine how significant the change is.

• They are used to develop test cases to test the system to see if it

functions as needed.

• They are used when modifications or enhancements are proposed to

ensure that the new change does not unintentionally replace

previous functionality, and that the new requirement fits within the

scope of the system's overall functionality.

• They are used to test a modified system to ensure all previous

functions, as well as the new functions, perform as needed.


Microsoft. (2009). Microsoft application architecture guide, 2009.

Retrieved from‐us/previous‐versions/msp‐


Mitre. (2018). Systems Engineering Guide—Analyzing and Defining

Requirements. Retrieved from



© 2023 University of Maryland Global Campus

All links to external sites were verified at the time of publication. UMGC is not responsible for the

validity or integrity of information located at external sites.


5 of 5 2/7/2023, 5:35 PM