Internet users are made up of people of all ages, experiences and abilities and anyone should be able to use the internet as easily as anyone else.
Approximately 1 in 7 people have a disability or impairment. In particular, people with impaired vision, cognitive disabilities or certain physical disabilities may find interacting with web applications challenging.
Spending time thinking about the design of your site and applying some simple principles and techniques can dramatically improve the way everyone experiences your app.
Your audience could be made up of a mixture of people so it's important that you cater for them all by designing with accessibility in mind.