This is the terminology list I wish I’d had to start with. A page with content something like this should be prominently linked in a post stickied where beginners will find it.
Input - An incoming datasource. Each input has an associated “node” identifier and a “key” sub-identifier.
You can’t really do anything with an input except hang a single chain of “feed” processes off it.
Node - a grouping identifier for your inputs or feeds.
Key - a sub-identifier for items within each Node.
Feed - A series of operations (process nodes) to execute against all new data coming to an Input. Each “process” (step) in a feed seems to get stored in a time-series database, usually either phpfina or phpfiwa.
Most of the interesting ones require php-redis, which doesn’t exist on all hosts.
Virtual Feed - A feed which hangs off any other process node.