This API lets you create websites via "addSite", update existing websites via "updateSite" and delete websites via "deleteSite".
When creating websites, it can be useful to access internal codes used by Piwik for currencies via "getCurrencyList", or timezones via "getTimezonesList".
There are also many ways to request a list of websites: from the website ID via "getSiteFromId" or the site URL via "getSitesIdFromSiteUrl".
Often, the most useful technique is to list all websites that are known to a current user, based on the token_auth, via
"getSitesWithAdminAccess", "getSitesWithViewAccess" or "getSitesWithAtLeastViewAccess" (which returns both).
Some methods will affect all websites globally: "setGlobalExcludedIps" will set the list of IPs to be excluded on all websites,
"setGlobalExcludedQueryParameters" will set the list of URL parameters to remove from URLs for all websites.
The existing values can be fetched via "getExcludedIpsGlobal" and "getExcludedQueryParametersGlobal".
See also the documentation about Managing Websites in Piwik.