Google Play Books was originally conceived as Google eBooks in December 2010. In addition to being an eBook stor, Play Store allows users to upload documents in a variety of formats and have them synced between devices. Like Amazon Kindle and Apple’s iBook store, authors can self-publish and sell their works.
There is an official app for Android and iOS, as well as a rudimentary web interface. The apps have a number of features like highlighting, notes, and a night mode that adjusts to the time of day.