Zotero is a free, open source application/software, which enables users to manage bibliographic data and to store web-page snapshots and other electronic objects. Also it gives the possibility to the users to manually create their own bibliographic database, in software version, by adding references directly from other bibliographic databases. Through a separate add-on, it also allows citation in text (in Microsoft Word and OpenOffice.org Writer) and can automatically create bibliographies in various formats (such as APA and MLA).

Zotero is used to manage bibliographies and references when writing essays and articles. On many major research websites such as digital libraries, Pub Med, Google Scholar, Google Books, Amazon.com, and even Wikipedia, Zotero detects when a book, article, or other resource is being viewed and with a mouse click finds and saves the full reference information to a local file. If the source is an online article or web page, Zotero can optionally store a local copy of the source. Users can then add notes, tags, and their own metadata through the in-browser interface. Selections of the local reference library data can later be exported as formatted bibliographies. Furthermore, all entries including bibliographic information and user-created rich-text memos of the selected articles can be summarized into an HTML report.

Source: Wikipedia

For installation and any further information about Zotero click here.