Some input devices for physically challenged computer users include specialized keyboards, mice that are operated only with a thumb, voice recognition software and tools that provide keyboard and mouse input via blowing air into a device. Some examples of output devices include Braille printers and speech output. Both input and output devices can be helpful for those who are blind, deaf or have limited functionality of their limbs.
Users who are unable to type with their hands can use tools that translate their speech into text on the screen or respond to puffs of air to perform commands in computer programs. Blind users can benefit from software that speaks what is on the screen, while deaf users can benefit from software that displays captions for spoken text. Braille printers are useful for printing out digital content in a format that is readable to blind users.