Apollo GraphQL Query hook has an option called partialRefetch and the docs state:

If true, perform a query refetch if the query result is marked as being partial, and the returned data is reset to an empty Object by the Apollo Client QueryManager (due to a cache miss). The default value is false for backwards-compatibility's sake, but should be changed to true for most use-cases.

Sadly I don't fully get it by reading the docs and searching online.

• What is different for queries using this parameter?
• When to use it?

Please go ahead and ELI5!