As in the official site says, citeulike is a free service for managing and discovering scholarly references. Now, more or less, there are 3,133,552 articles in this site. It is described as an easily store references you find online, where you can discover new articles and resources, share references with your peers, find out who’s reading what you’re reading and store and search your PDFs.
Through helping users keep track of their own bibliographies, this page, creates an environment that facilitates sharing academic resources. The basic functionality of the tool is simple: when researchers sees a paper on the Web that interest them, they can click a button and have a link to it added to their personal library.
CiteULike works because it is very useful for every user. It automates a repetitive bibliographic management task and it offers a complimentary alternative to search engines and databases of academic literature through socially mediated retrieval and discovery of papers.