Collections are a Zotero feature that helps you better organize your references. They are similar to file folders on a computer (and even share a similar icon), but a Zotero reference can be in more than one collection at a time. As an example: an article about personal data privacy can be found in your general Library, a collection on data, and a collection on social media.
To create a a collection, click on the button that looks like a folder with a green plus sign. You can drag and drop references you already have into that collection.
Do you have a collection of PDFs on your computer from old classes or another project? Zotero can help you add citation information for them. To add PDFs to Zotero and find their metadata, use the following steps:
For more on how this process works, check out Zotero's retrieve metadata guide.
You'll find the information Zotero collected about your reference on the right side of your library after selecting a reference. Citation information is in the "Info" tab, and you can edit any field by clicking on it except for "Date Added" and "Modified."
Notes: These are for your personal use. Some suggestions for what to put here are quotes, summaries of the resource, or why you chose to save and cite it.
Tags: Tagging references can make it easier for you to search for them. Especially with database articles, tags are often automatically downloaded.
Related: This allows you to link a resource to another item in your collection. This can be especially useful for tracking which sources refer to each other.
If there is a PDF with an article citation, Zotero will often save the PDF automatically to the citation. If it does not save automatically, check your Zotero Preferences. You may need to change some Zotero settings.
You can also attach files and PDFs manually to citations.