Keep personal copies that aren't tied to a specific storefront or device license.

Easily switch between EPUB (used by Nook, Kobo, and Apple) and MOBI or AZW (used by older Kindles).

A major milestone occurred in 2016 when over were released DRM-free (Digital Rights Management-free). This allows readers to:

Official digital releases became standard practice around 2000, starting with the series. Today, nearly the entire back catalog has been digitized by publishers like Pocket Books .

For those building a digital library, several legal avenues offer extensive collections: