When an ebook is read online, it is viewed on a particular ebook platform. The platform "hosts" the ebook and usually includes various options for interaction, for example, printing pages, searching the text, and highlighting sections.
The Library's ebooks are hosted on a number of different platforms, which is why they don't all look the same, or have the same functionality.
Learn more about where to find eBooks on the Find ebooks page, and how to use the various features on the Use ebooks page.