1) Mendeley is a free reference and citation manager that allows users to gather, organize, and annotate research papers. It includes desktop, web, and mobile apps.
2) Mendeley can import papers from a user's computer, watch folders to import new papers automatically, and import papers from supported databases using a bookmarklet. It allows highlighting and annotating papers.
3) Mendeley generates bibliographies and citations in Word and LaTeX documents. It syncs data across devices and has search capabilities. However, it does not directly search external research databases.