Zotero (pronounced 'zoh-TAIR-oh') is a free reference manager. It is designed to store, manage, and cite bibliographic references, such as books and articles. In Zotero, each of these references constitutes an item. More broadly, Zotero is a powerful tool for collecting and organizing research information and sources.
It allows you to import PDF copies of articles, add notes to what you save and to work collaboratively with others. You should be using Zotero if you are writing a paper, preparing a presentation or doing any kind of research. It will save you time and frustration!
Maybe you'd like to see what Zotero can do before going through the tutorials. Watch this quick video to decide if Zotero is for you.