Size

Many people like to fit a maximum amount of information onto a single screen. However, there are also many who find small type difficult, or even painful, to read. Users with severe visual impairments will probably choose accessibility aids, such as a screen enlarger, that can zoom in on a portion of the screen. A much larger number of users may have no trouble reading 12 point text on the computer screen, but find it difficult to read text in smaller sizes. Other users may not have trouble reading text, but suffer from headaches and eyestrain at the end of a day. These users do not view small type as a problem of accessibility; they view it as one of usability.

Although an application might work fine for a user on one computer, it may be unusable on another computer. Applications that are designed to look good at standard resolution may have their information shrink to near invisibility when run on a high resolution monitor, or information may appear inaccessibly off the screen when run on a small, pen-based computer.