[jocampo]

A non DRM epub book will not be tied up to an specific ereader. In other words, it can be easily converted to mobi and read on a Kindle. The same is also true for a non DRM mobi book. Even with DRM, a person with desire and the proper scripts, can also remove the DRM protection and read that on whatever device they like or want.

Is a fact, Amazon leads the book's market here in USA and all the other companies are trying to compete to get a bigger piece of the cake. One went to bankruptcy already and B&N is struggling now. Sony just started their own bookstore, same for Apple. Whoever has doubts about that, go online and check Amazon's quarterly reports for past 5 years or so. Then compare to B&N or any other similar bookstore here in USA.

Here in USA there is no other online bookstore with bigger variety of books (electronic and pbook) than Amazon. You can even find rare computer or Spanish books, not available in any other store.