E-book is short for electronic（电子的）book. It is usually read on personal computers or mobile phones ore-book readers.
Earlier, only some groups of readers would read e-books. And the subjects of e-books were not too many. With the development of the Internet, people find more knowledge in e-books. This is why e-book business is developing quickly.
E-books have many advantages（优点）. First, they save time. We don't need to go to a bookstore to buy paper books. Besides, we can find the topic we want to know on the Internet. And then we can quickly get many e-books on similar topics. Second, e-books save money. Some e-books cost a little money, and there are millions of e-books on the Internet. And we can read them for free. Third, because e-books are not made of paper, people don't need to cut down so many trees anymore. It's good for the environment. Fourth, e-books make reading more convenient. You can carry hundreds of books with you in a small computer or any e-book reader. But that's also e-book's disadvantage（缺点）. They need a personal computer or e-book reader. And the information of e-books can be lost. However, e-books provide us with a new way of reading. That's good.
