One of the most convenient ways to update your website content is to upload it through FTP. FTP (File Transfer Protocol) is a standard network protocol that allows transferring files between two hosts (for example, your computer and a Plesk server). Plesk acts as an FTP server, while users should use some FTP client to access the directories on the server. Plesk provides all main FTP features:

• Authorized access to the server. Learn more in the section Changing FTP Access Credentials.
• Multiple user accounts for collaborative work. Learn more in the section Adding FTP Accounts.
• Anonymous FTP access: The access without authorization that may be used, for example, to share software updates. Learn more in the section Setting Up Anonymous FTP Access.

More information can be found in Plesk’s documentation located here: https://docs.plesk.com/en-US/12.5/customer-guide/ftp-access-to-your-websites.69544/