An Action List is a sequence of streaming processes and track processes that can be rendered at the touch of a button. (For obvious reasons, spot processes cannot be used in this fashion.) You create one by inserting either the current process manager render chain or a track process into the list, followed by another, and then another... until the desired sequence is created. You can of course save and later recall these lists.
Action lists understand cue points and regions so you can render the current region, the regions in defined categories, or all regions outside of a chosen category.
Furthermore, you can use actions lists as the basis of batch processing paths, rendering individual file or group of files by dropping them into the appropriate source folder or by dropping them directly into the Pending Files window in the batch processor.