If you've ever used some of the many online citation generators such as EasyBib or Noodle Tools, you're going to enjoy the more robust time-saving and organizational features of Zotero.
Many comparable products and programs exist. Mendeley, RefWorks, and Endnote are some you may know. Pricing structures vary from free, to “freemium,” to a monthly or annual fee. To learn more visit their websites or check this handy comparison page.
Or, read this thorough yet concise Why Zotero? page.
Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share your research sources.
Take a look at what you can do with Zotero:
ZoteroBib - Requires no account or software installation and provides a quick, reliable tool for creating one-off bibliographies. ZoteroBib enables you to build bibliographies in a variety of citaton styles and format basic in-text citations. You may re-use and edit bibliography you create--it will remain available in your browser until you clear it.
Not sure which to use?
The Zotero/ZoteroBib website offers guidance for choosing the option that is best for you.
There are a number apps and programs compatible with both Android and iOs. They are listed and described on Zotero's website. Some apps are third-party products, but a Zotero app for iPhone and iPad is available from the Apple Store.