Resources are the hierarchical objects you create and interact with within a Zenkit product. They are hierarchical because some resources contain other resources. In less abstract terms: 
In Base, these are called "workspaces", "collections", and "items". In To Do these are called "folders", "lists", and "tasks".  In Hypernotes, these are "notebooks", "notes", "blocks", and "tasks". These may go by other names in other Zenkit products.

In the end, an item in Base is the exact same resource as the task you see in To Do, Zenchat, Zenkit Projects or Hypernotes. The different apps just represent different ways to access, view, or work on the same resource.

Important terms to know:

Resource Owner - The resource owner is the product in which the containing resource was initially created (e.g. if you connect a collection in Base to Zenchat, Base is the resource owner, even if subsequent tasks/items are created in Zenchat).

Containing Resource - A resource that contains other resources (e.g. a workspace contains collections, which contain items). Other Zenkit users may be added to containing resources as members (e.g. a list member in To Do, a notebook member in Hypernotes).

Transferring ownership of resources

To transfer the ownership of a resource, simply open the collection-, list-, project- or notebook settings and click on "Zenkit Suite". You will see all products listed. When they are already connected you will see "Transfer" next to the product.

Not all resources can be transferred to every Zenkit product. A chat from Zenchat for example can not be transferred to To Do.

After having clicked "Transfer" you have to confirm the action by clicking "Transfer" again.