Ben, I really need your book on USB, but I can't get - is it sold in the .pdf form? ("kindle" is not clear what the format is for me).
Kindle is in fact the name of a specific format, namely, the format developed for the original Amazon Kindle e-reader about ten years ago, and subsequently used in Amazon's cloud and webapp distribution methods as well. It is a proprietary format, and one designed with DRM from the outset, which is great for authors but also tends to leave your books at Amazon's ransom (as the webapp and e-reader only keep a handful of books in local cache at a given time, with anything you haven't read recently only stored on their cloud servers).
While Amazon have, for the most part, operated their Kindle services in good faith, there have been some problems (fewer than, say, iTunes, but they have occurred). In general, though, it is a good service, but if you have an ideological problem with DRM (as many do), it can be seen with distaste.
Personally, I have no issue with DRM in principle; assignment of authorship credit and support for micro-payments (ones which actually lived up to the name, that is, with lower boundaries in the range of a ten-thousandth of a cent) were two of the primary goals
, and for good reason (they still are, though I don't know how far the released version that finally came out in 2014 goes in the planned support - yeah, it took them 53 years to get half the job done, I know, I know, but I still think the ideas are sounder than those at the heart of most current systems).
However, ideology aside, DRM got a bad name as much from the many terribly designed and heavy-handed most approaches to 'copy protection' over the years - and the fact that it is, in a real sense, counter to the general behavior of computers - as it did from worries about loss of freedom. and while I have some real problems with it in practice, the fact remains that the alternative is to abandon copyright and for-profit authorship entirely.
Kindle is, fortunately, a relatively light touch when it comes to its requirements and restrictions, and I have several books which I have purchased in this way. There is some trepidation over the fact that I don't really have control over them, but that holds true with anything 'on the cloud' (e.g., distributed and mirrored over remote servers through automatic means - I would complain about the term 'cloud' being cybercrud
and doublespeak, but I've already beaten that horse to death long since).