First of all, I must answer the obvious question: What is an ebook? An ebook is a book that has been digitized by a computer program and its text has been converted into a format that is more easy to take with you anywhere. The text of the book has become a special text file which can be downloaded into a PDA, a special item designed to read ebooks or even on your mobile phone!
Thanks to this technology we can bring with us a whole library to read when we want, or search for words or sentences quickly. This advance in technologies makes finding information so much faster than we could get by the traditional method, in addition to solve the problem about two people searching for the same book. With this aplication serching books will be easier at any time, and distribution could be free, it's like a gift culture. Besides saving money on paper, ink, distribution, etc., and avoid the felling of trees to produce best sellers.
Thanks to this system can preserve the information of the original books because the books can be damaged, but not ones or zeros.
On the other hand, perhaps the fact of reading a book that was not made from paper is not very good for your seeing, but there are specific ebook readers that regulate the brightness of the screen and the “ink” are not bad for you in the case you could be reading for too long.
I used:
http://en.wikipedia.org/wiki/Ebook
http://www.ebookmall.com/aboutebooks.htm