There are three main tools used by blind and low vision computer users.
The most common is screen reading software, which is a program that, as you might guess, reads out loud what is on the screen. Screen readers don't always work with every other program, or every website, but they are a powerful tool for accessing digital information without needing to ask for the assistance of a sighted person.
In addition to the robot-voice output, some screen readers can also send information to a refreshable braille display. A refreshable braille display is a row of braille cells. Each cell has movable pins that rise up or fall back down to make the shapes of braille characters. Some refreshable braille displays, intended for use with cell phones and pagers, have enough cells to display just one or two words at a time, and some of the larger ones can display up to 80 braille characters at a time.
If the person still has some usable vision, they may elect to use screen magnification software. Screen magnifiers don't just make everything bigger. They can smooth the edges of text, change colors, and add other effects to the display to make it easier for a person with limited vision to use. Some magnifying programs also have a built-in screen reader, or are designed to be compatible with another screen reading program.
Also on the market are braille notetakers. Braille notetakers are computers that are designed to be accessible to blind people. They can best be described as a halfway point between a PDA and a laptop. They usually do not have any kind of visual display, but have audio output and a built-in refreshable braille display. Popular software packages for braille notetakers allow web browsing, email, audiobook playback, word processing, and even GPS navigation.