Alternative text description
This is text that describes the content of an image but is not normally displayed visually to a user. It is usually only accessed through text-to-speech or screenreaders, or if the user chooses to have it displayed. For example on a web page, alt-text for an image is read aloud by any text-to-speech software being used, and can also be available visually by moving the mouse over the image. It is thus helpful to a blind user who cannot see the image, and to a partially sighted user who is reading visually but may find the image hard to interpret.
Braille display
This is a piece of hardware attached to a computer or mobile device containing rows of pins which can be raised and lowered to construct braille, and is used to display text from the screen to a blind user reading by touch. Braille displays typically contain only one line of braille along with navigation buttons to navigate through the content shown on screen.
Enhanced edition
Enhanced edition eBooks can contain audio and video clips in addition to the text of the printed version of the book. They are dependant on the reading system to play the enhanced contents. Audio description and captioning are needed to make such enhanced eBooks accessible.
Fixed layout eBooks
Fixed layout eBooks preserve the layout of the page and do not reflow. Font style and size is also generally fixed in these types of eBooks. They are popular for graphic's intensive layouts as found in cookery and travel books for example. This format is also popular for reproducing magazines as the look and style of the printed version can be preserved.
Navigational information
This assists a user to move around a book. They may read it straight through but they may use a table of contents to navigate to a specific chapter; they may use a bookmark to find a previously marked location; or use a "Find" facility to locate a particular word or phrase.
Reading system
This covers both hardware devices for reading eBooks, and software programs and apps on a computer or mobile device, such as a phone.
Reflowable eBooks
In a reflowable eBook the screen pages are dynamic and automatically adjust when font sizes are increased or decreased for example. Reflowable eBooks offer the most potential for purchasers to customise their reading experience according to individual needs and preferences.
Screenreader
This is a software application that runs alongside other programs and reads aloud whatever is displayed on screen, enabling a blind person to use a computer or mobile device such as a phone to navigate menus and read within applications.
Synthetic speech
This is artificial speech generated by a computer. Sounds are based on a dictionary of pronunciation and/or phonetic knowledge. Many different synthetic 'voices' are available to cover different languages and frequently offer both male and female voices. While there have been improvements in the technology related to synthetic speech in recent years, computer generated voices are easily identifiable and not comparable with human narration.
Text-to-speech
This software, available on many eBook reading systems, renders digital text as synthetic speech, allowing someone who cannot see the text to listen to it instead. Some text-to-speech engines in eBook readers only allow reading of books, but do not provide audio access to menus, thus not functioning as a screenreader.