I don't think we need to repeat the whole 100 page discussion on DRM here. A quick search of MobileRead will quickly reveal enough to sate most people's desire for such an inconclusive mess. (There's even one that I started!

)
DRM comes in many forms, some more intrusive than others. As self-published authors we have choices. Like most other facets of self-publishing, this requires some self-education. We must read what is
actually on offer and make our own choices as best suits our own work and our own natures.