NVDA is an open source (freely available, asking only a donation) screen-reading application that can be used on several platforms: PCs, Macs, Linux, etc. Screen-reading applications are used by blind and low-vision users, and with individuals with reading disabilities, to access the internet and electronic books.

Unfortunately, screen-reading applications have been very expensive. This was bothersome to two young Australian software developers, Michael Curran & James Teh, who happen to be blind. To correct this situation, they started a not-for-profit organization called NV Access and went to work to create a free screen-reading application. This application, NVDA, is used by blind people all over the world.

Here is a link where to James and Michael's website: https://www.nvaccess.org

Here is a link to a site that tells the story of how NVDA came about: https://www.hostingadvice.com/blog/nv-access-provides-open-source-screen-reading-software-for-the-vision-impaired/

Here is a TEDx Brisbane presentation in which James and Michael tell their story, and explain their goals: 

https://youtu.be/uPo30QUVGjg

Here is a link to a very helpful NVDA Keyboard Shortcuts page: https://dequeuniversity.com/screenreaders/nvda-keyboard-shortcuts