Recommend a software library, tool, book, research paper, blog, forum, or other resources
Questions asking us to find or recommend tools, libraries, programming languages, resources (including books, blogs, tutorials, and examples) are off-topic for Programmers as they tend to attract opinionated answers and spam. Instead, describe the problem and what has been done so far to solve it.
Stack Exchange is not designed to be a book, library, or link review site. It just doesn't work well that way. Asking for libraries and tools often attracts spam answers where the person answering it just drops a link to some library in an answer, without explaining anything.
Questions like "What is the best book to learn Java from" are incredibly broad, polling questions that have no right answer, only opinions. There are hundreds (if not thousands) of books on Java. Often times these books become outdated as fast as the technology does.
We do book review and suggestions poorly
One of the classic recommendation questions is that of a book.
We do book reviews very poorly. All the answers that one gets are opinions and this is fundamentally a poll of opinions. This is to say nothing of that the technology behind them changes too. There are indeed timeless books (and many have written on the subject), though their value is a matter of debate.
Between the polling nature of the question, the opinions people have on certain books, the constantly changing target, and the site's history of producing poor quality answers to these questions (and not moderating them), asking for a book suggestion is very likely to get closed and down voted.
Asking for a link to something or statistics
This is a subtler meaning of the 'favorite off-site resource' part of the wording of the close reason. Asking a question that doesn't draw upon the community's expert knowledge as programmers but rather asking it to be a crowdsourced search engine falls into this area.
Links to things suffer from link rot. Statistics become out of date over time. Neither of these contribute significantly to the collective knowledge of problem solving that the Q&A format provides.
An example of this is someone asking in 2012 "What is the market share of Android vs iPhone?" This information would be out of date in a few months as new numbers come out and someone else would ask in 2013 "The question [link] asks about the stats, but they are all for 2012. What is the market share for android vs iPhone in 2013?" And again, this information would be out of date and prompt another question.
Asking for information about statistics, or more generally, asking us to search for some data for you is off topic because of these problems:
- No actual problem to solve
- Not drawing from expert knowledge of the community
- Will suffer from link rot or become out of date
Furthermore, external resources may move or be deleted for a variety of reasons. Perhaps a particular site reorganizes its links without setting up redirects. Perhaps an organization goes out of business or discontinues product X or library Y.
In addition to the reasons stated above, external resources tend to be transient. Whatever tool, library, or other resource who requested might not exist in five years or be otherwise readily available. This has the effect of making an answer utterly useless.
If one asks for a library to perform function X, and the answer links to web site Y, and either function X or web site Y cease to exist as defined in the answer, that answer is now useless.
This is one more reason why questions like this tend to be of low value and are off-topic.
Is there a place where I can ask such questions?
Asking for software recommendations is on topic at Software Recommendations. However, if you decide to repost the question on that site, the required information for posting a question has a much higher threshold. From the ground rules and What is required for a question to contain “enough information”, you will need to describe your specific need in detail. If you are unsure how to frame such a question, please ask in the SoftwareRec chatroom before posting.
[Why was my question closed as "Off Topic - Requests for Recommendations?"](http://meta.programmers.stackexchange.com/a/6487/)