1.  Zotero can keep track of your library’s data across multiple computers.  Zotero is able to sync your library across multiple computers because Zotero can store your data on their servers.  There are two kinds of data that Zotero can store.  The first is just-plain data, or the metadata associated with all of the citations you have – the titles, authors, journal titles, tags and notes you have for those citations.  The just-plain data is synced on Zotero’s servers and there is no limit to how much of this kind of data you can store on Zotero’s servers and therefore sync across multiple computers.

2.  The other type of data are files – the attachments that your citations may have such as PDFs or screenshots.  These files can quickly take up a lot of space, so Zotero only gives users 300 MB free server space for this type of data.  To give you a picture of how much 300 MB is, a general rule of thumb is that one PDF averages 1 MB.

3.  If you need to access more than 300 MB of space from multiple computers, one option is to pay for additional storage space via Zotero. To access Zotero's cloud storage, from the Zotero tool bar on a PC choose Edit>Preferences>Sync (on a Mac choose Zotero>Preferences>Sync) and sync your files to Zotero's cloud storage using the Zotero pull-down option.

4.  Another option is to use WebDAV storage space.  There are some free WebDAV storage options.  Google "free WebDAV" to see a current list of what is free and recommended.  Some university departments will provide WebDAV space for their constituents.  If you have WebDAV space available to you, enter the site address for your WebDAV space so that Zotero knows where to store your files.  For questions about setting up WebDAV space, search the Zotero forums for suggestions from other Zotero users.