Chapter 03

How to Use This Resource

Understanding the four pillars, three compliance levels, and impairment categories that structure the WCAG 2.2 guidelines.

The Four Pillars of Accessibility

WCAG is organized around four core principles — often abbreviated as POUR. The guideline numbering reflects this: a guideline starting with 1. is about Perceivability, 2. about Operability, and so on.

1. Perceivable

This principle is about making sure the PWDs (People With Disabilities) can comprehend the elements of information presented to them on the screen, and reach the same in the most logical path.

2. Operable

This principle is about making sure the PWDs (People With Disabilities) interact with the interactive components on the screen, irrespective of their abilities. This means supporting physical devices to help them navigate the information and ensuring the app is fully functional within the provided constraints.

3. Understandable

This principle is about making sure the PWDs (People With Disabilities) can easily follow the information on the screen. This means making the functionalities predictable and arranging the content to minimise confusion.

4. Robust

This principle is about making sure that the information presented is compatible with a wide range of devices; current, past and in the future. This means making sure that the content is available to the PWDs in a similar fashion, irrespective of the tools they are using.

The WCAG Chart

Here is the lay of the land. This chart has helped me understand the 13 themes and the guideline structure in the entire WCAG. You can download a PDF version of the following chart from the link below.

POUR principles chart showing the 13 themes and guideline structure across the four WCAG pillars

Three Levels of Compliance

Compliance levels are stacked — to achieve AA, you must first pass all A criteria.

Level	Criteria Count	What it means
A	32 success criteria	Basic level. Essential accessibility — without it, some users cannot access the content at all.
AA	24 additional criteria (56 total)	The globally accepted standard. Required by most accessibility laws worldwide.
AAA	31 additional criteria (87 total)	Enhanced accessibility. Optional — but aspirational. Not covered in this handbook.

Impairment Categories

The guidelines in this handbook are tagged by which type of disability they serve. Here's how they're classified:

The Blind

Complete blindness; rely on screen readers.

Visually Impaired: Severe

Colourblindness, tunnel vision, glaucoma.

Visually Impaired: Mild

Blurry vision, age-related changes, screen glare.

Hard of Hearing

Partial or full hearing loss.

Motor Impaired: Mild

Tremors, shaky hands, limited fine motor control.

Motor Impaired: Severe

Absence or inability to use a limb; may rely on switch access.

Neurodiverse

Differences in comprehension, learning, or attention.

Elderly

Age-related changes in vision, hearing, cognition, and motor ability.

Note on Elderly: Although not a disability, this section covers problems associated with advanced age like loss of contrast, loss of vision, loss of hearing and reduced memory and cognition. This may result in inability to learn new things quickly and keep with the changing tech landscape.

A Note on Tools

This handbook is tool-agnostic, but the author is a Figma user. Plugin recommendations and testing advice lean toward Figma — but the underlying theory applies to any design tool.

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