Accessibility in a system refers to how usable a system is for a user. There are many types of users out there and no two are exactly alike — some users have perfectly adequate vision while others do not, some users operate a system using a standard mouse and keyboard while others are not afforded the same dexterity to be able to operate with these standard tools.
It is important to consider all sorts of users when making design decisions. In this section we will focus on two major sets of impairments, physical and visual, and how they should be considered when designing an interface.
Why should I care about accessibility
Because no two users will use a system in the exact same manner, it should at least be possible for all users to have the same experience using a system or not be impeded by it.
A very common impairment to consider is vision: many users have different settings for their text sizes on a device, and it is important to consider this when creating a system. If a system is only designed with the standard text sizes in mind, the experience a user may have while using larger text settings will likely suffer.
A system should be adaptable to any type of user.