Publishing is the process of copying your projects' information to the Content Delivery Network (CDN) so it is available to use with websites. You should publish after each edtiing session, but not during the session, as it takes a few seconds to complete. An editing session, therefore, might consist of browsing the library, creating and adding fonts to projects, assigning fonts to selectors, etc, and then publishing.
Some API commands will publish automatically after each invocation unless you set a parameter (wfsnopublish) directing it not to publish. We recommend that you use this parameter, and then explicitly call the "Publish" API command once your edits are complete.