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This is a generalization but so far it has served to be a rather accurate one. I like to use books that are written by university professors. The most obvious reason being that the books are written by people who know how to teach and what it is that they are teaching. Teaching from a book is not something that everyone can do. Indeed many have failed at this task. However, not every professor can be a good writer either.

Generally, for books that are meant to instruct and educate on subjects that are more theoretical than just being practical (compare a book about OpenGl and a book about computer graphics or a book about SQL and a book about database system), the professors do it the best. They have been teaching for so long and they know how people learn this stuff. In short, books that are supposed to teach you the foundations of the fields must be written properly.

Another observation I have made is the fact that good books have websites. And the websites are hosted on the university pages. Moreover those websites are updated frequently. This shows that the author is willing to take the effort to maintain the website himself or herself. This dedication to his or her work implies that the author is not out to get money for his book. Moreover it shows that the author takes pride in his or her book. Books that have commercial websites are generally useless. Websites that are under the publisher's domain are generally just thrown together and do not contain anything useful. These websites are seldom updated and contain only the sparsest of materials.

On the other hand, websites that are maintained by the professors themselves are useful. They usually have the latest lecture notes and list of errata. And also they have a comprehensive list of supplementary materials. This list is particularly relevant for books on CS since the field changes rapidly. On these same websites, you can also find the views of the professor on matters that might not be directly related to the book. A good writer is always finding new things to write about. A good sign that the author is a good one is to check when was his latest writing. It need not be a new book but it should be an article that he has written by himself. The article could be something simple, maybe discussing the issues of nature. The point is: people who write in their free time are always better authors. They write because they have strong feelings about things and are passionate about sharing them.

It is even better if the university that the professor comes from uses that book too. And, of course, it will be excellent if the professor is teaching that class too using the same book. I am usually wary of books that have undergone many editions yet the professor himself or herself has not been using that book to teach. Changing chapters around is not a good reason to come up with a new publication. There is no reason to come up with a new edition unless you have discovered a serious flaw with your previous edition. In fact, books that have new editions each year are generally the most useless books on the face of the earth. The authors are probably under pressure from the publishers just to come up with a new book. Pity those poor students who own the worthless books and cannot even sell them now.

Good books always come together with excellent materials. They do not include a CD that is not necessary. Why include a CD unless you are fairly sure that the material is hard to obtain? Especially in the field of CS, whatever is on that CD is probably obsolete by the time the book ships. So instead of having a CD, maintain a website instead. By excellent material, I mean that the book contains a list of references at the end of each chapter. It also contains certain features that help you learn. For instance, some icons to quickly identify important information. And inserting a line of joke or two between the text is always a good idea. Authors with a sense of humor can make the material fun and enjoyable. Of course the purpose of the book is still to read like a book so do not make it so informal until it reads like it was just a recorded version of a lecture.

Furthermore, I also like reading the preface to the book. I like it when the author mentions how the book is structured and why he or she chose such a methodology for presenting the book. A preface that describes what the book teaches and not why or how it is done is not very useful: I can find out what the book teaches through the table of contents. While reading the book, I like finding out if the author really exercises what he or she preached in the preface.

Last but not least, authors that are considerate will ensure that they do the following:

• Put the diagrams on the same page as the paragraphs that describe it to minimize page flipping.
• Always finish the last sentence of the page on the same page so that the reader does not need to flip over to the next page.
• Write in short simple sentences.
• Leave some margin on the side for the reader to take notes.
• Use color only where it actually serves to illustrate things better. Having the titles appear in blue is not really useful.

In short, those are the trends of good books that I have personally witnessed. Your personal experience with books will vary but I am fairly certain that if you like to read and learn from books, you will agree with me on some of the things I mentioned.