As digital accessibility is the practice of ensuring technologies are accessible to people with disabilities, it can be helpful to consider common types of disabilities and how they impact one's ability to use different technologies.
This list is not exhaustive, but may help you understand different types of disabilities, including invisible disabilities, and the techniques that may remove barriers associated with those disabilities.
Visual
Examples: Blindness, low vision, colorblindness (complete or partial), cataracts
Techniques: Providing text-based alternatives to media, using non color-based means of identifying different series of data on a graph, ensuring content is presented correctly when zoomed in
Auditory
Examples: Deafness, hard of hearing, tinnitus
Techniques: Providing closed captions on videos, adding on-screen alerts anywhere audio is used to indicate an error message
Motor / Physical
Examples: Missing digits / limbs, using a wheelchair, tremors due to conditions like Parkinson's Disease.
Techniques: Ensuring all functionality can be completed using the keyboard
Cognitive
Examples: Dyslexia, limitations in short or long-term memory
Techniques: Use easy-to-read fonts, avoid jargon, define acronyms and abbreviations on-screen
Neurological
Examples: Epilepsy, vertigo
Techniques: Avoid rapidly flashing lights, avoid auto-playing videos, and ensure auto-scrolling content like image sliders can be paused.
Temporary / Conditional
Examples: Broken bones, limited vision at night
Techniques: The same techniques that assist permanent disabilities will typically work here, but this group may be less likely to identify as having a disability, so having accessible technology is especially important here, as the user may not know to otherwise ask for an accommodation.
Concurrent
Examples: Limited vision AND broken bones in hand. A person has limited vision, and can typically navigate most websites on their mobile device by pinching the screen to zoom in and holding the phone close to their face. They have an accident and break the bones in their dominant hand, making it painful or impossible to zoom on their phone while using their other hand to hold the phone. A new, temporary disability has made an unrelated disability more prohibitive.
Techniques: It's not realistic to foresee every possible combination of conditions that could produce accessibility barriers, so follow all the other accessibility best practices, and be prepared to offer accommodations as-needed.