Blackboard Ally (or simply just 'Ally') is a tool which allows you to download alternative formats for common documents to make your learning resources more accessible.
Files uploaded to Blackboard* are automatically given an Ally icon (looks like an 'A' with an arrow next to it) to the right of the file name, clicking on this opens the option to download the following different formats, whatever your need:
* currently available in Blackboard courses, for items created using the in-built text editor and for files uploaded as PDF, Word, PowerPoint, OpenOffice/LibreOffice, and HTML.
For further information either download the guide from this page (located to the right-hand side) or see Blackboard's own guidance: Accessibility in Blackboard