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POUR: The 4 Principles of Accessibility

Accessibility Best Practices

Accessibility is giving equitable access to everyone along the continuum of human ability and experience. Accessibility encompasses the broader meanings of compliance and refers to how organizations make space for the characteristics that each person brings. As it relates to websites and digital content, the 4 Principles of Accessibility were born.

There are four main guiding principles of accessibility upon which Web Content Accessibility Guidelines (WCAG) have been built.  These four principles are known by the acronym POUR for perceivableoperableunderstandable, and robust.  POUR is a way of approaching web accessibility by breaking it down into these four main aspects. Many of the technology challenges faced by disabled people/people with disabilities can be described using one of the POUR principles.


Perceivability means the user can identify content and interface elements by means of the senses.  For many users, this means perceiving a system primarily visually, while for others, perceivability may be a matter of sound or touch. New and emerging technologies may include sensory cues for smell and taste; these would also be considered examples of "perceivable" technology.


Operability means that a user can successfully use controls, buttons, navigation, and other necessary interactive elements.  For many users, this means identifying an interface control visually and then clicking, tapping, or swiping.  For other users, using a computer keyboard or voice commands may be the only means by which they can operate and control the interface.


Understandable technology is consistent in its presentation and format, predictable in its design and usage patterns, concise, multimodal, and appropriate to the audience in its voice and tone.  Users should be able to comprehend the content and learn and remember how to use the interface.


Robust I.T. is standards-compliant and designed to function on all appropriate technologies.  Users should be able to choose the technology they use to interact with websites, online documents, multimedia, and other information formats.


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Credit Where Credit is Due

Critical annotation example in APA format is reproduced from "How to write annotated bibliographies" on the Memorial University Libraries website. 

Critical annotation example in MLA format is reproduced from "Writing an Annotated Bibliography" on the Saint Mary's University Library's website.

Accessibility and the Law

Accessibility means creating digital content for a wide range of users, including those with disabilities and users of assistive technologies. The goal is to remove barriers of access for all users without having to make accommodations. Accessibility specifically addresses disabilities, but accessible content benefits all users. 

It's the law.

It's WCAG 2.x compliance.

This Accessibility Resource Center (ARC) presents you with guidelines and resources to ensure your online content is in compliance with the law.

These guidelines are based on the international Web Content Accessibility Guidelines (WCAG) 2.x, set by the World Wide Web Consortium's (W3C) Web Accessibility Initiative (WAI).

Online Education User Challenges and Solutions

Accessibility at Prince George's Community College

Accessibility at Prince George's Community College 

The Library aids and provides services to qualified students with disabilities to ensure their effective participation in all college programs and services.

PGCC Campus Disability Support Services 

Hours: Monday to  Friday - 8:30 am - 5:00 pm
Location: Marlboro Hall, Room 2102
Phone: (301) 546 - 0838

Prince George's Community College is dedicated to the principle of equal opportunity in education, research, and service. The Library reflects this commitment by ensuring that collections, services, and facilities are accessible to all users. For further assistance or accommodation, please contact a staff member in person at any service desk or by phone, e-mail, or chat. 

Locating or Reaching Library Materials

Library staff members will assist with locating or reaching shelved library materials. Provide the location information of your items to the nearest service desk and a staff person will retrieve the items for you. 


  • Windows computers in the library offer standard Windows tools for accessibility -- magnifier, narrator, on-screen keyboard, and speech recognition. 
  • Computer number 23, located in the Research/Information Desk area, is equipped with an extra-large monitor and has JAWS and ZoomText installed 
  • The instruction classroom (A109) has an adjustable workstation
  • The second floor has an accessible cubical
  • Accessible parking spaces are available in lot I, adjacent to Accokeek Hall
  • The entrance to Accokeek Hall has push-button access on both sets of doors leading to the main lobby
  • The elevator on the first floor  

Electronic Resources

  • Most of the videos in the streaming video collections include closed-captioning
  • Some databases feature a text-to-speech option via ReadSpeaker 
    • The function converts text and streams the corresponding audio content without any software downloads or special plug-ins needed. Users can select any portion of text, or an entire article to be streamed as audio. These audio segments can also be saved as MP3 files for use on MP3 players for listening at a later time. (from Gale Databases to Feature Text-to-Speech Option via ReadSpeaker)

State, Local, and National Resources