What do you understand by Catalog in puppet?

The catalogue is a document used by the puppet agent while the Catalogueration of a node. Puppet agent downloads the catalog through Puppet Master. For every resource, the desired state is described by the catalog which should be controlled. A catalog is compiled in puppet with help of some resources of information of configuration. The first one is 'agent provided data'. The second resource is 'Puppet Manifests'. And the third resource used by puppet for compiling a catalogue is 'external resource'.