Depending on the title, the following formats may be available: Adobe DRM-protected EPub or Adobe DRM-protected PDF.
EPub is the standard eBook format that makes it possible to optimise and customise text and images for both large displays like a desktop computer and small screens like smartphones. Sometimes the format is also referred to as 'flowing text'.
PDF (Portable Document Format) is the standard format for document interchange created by Adobe.
Both formats are "Adobe DRM Protected" and must be linked to an Adobe Id.