Zotero is a free, easy-to-use citation manager that will help you collect, organize, cite, and share research. Using the web browser extension you can save articles, books, and websites you find to your personal Zotero library. And the best part about it is, you can share a Zotero library, making collaborating on a project or research paper easier than ever.
Citing the sources you use in your research is incredibly important for many reasons:
If you can't figure out whether or not to cite a source check out these guides
If after consulting these sources you still aren't sure whether you should be citing a source, CITE IT! It's better to have one extra citation than a missing citation.