docs/architecture/resources/README.md
Pulumi has four different types of resources. Provider Resources, Custom Resources, Component Resources and View Resources. We'll describe them below.
Provider resources are virtual (they only exist in the Pulumi state, not on any backend) resources, that represent a provider and its configuration. They are stored in state, and referenced by custom resources, so the engine knows which provider, with which settings was used to set up the resource, and so the same settings can be used for further update or destroy operation for a resource.
Custom resources are resources that are created in a provider. Custom resources often exist in a cloud provider, but this is not necessary for all resources (e.g. see the pulumi-random provider, that creates resources and stores all of the state in outputs, without creating any resources in the cloud backend)
Component resources are usually used as a container to group other resources together, and to create reusable components that consist of other resources. Similar to Provider resources, these resources are also virtual resources, and are only represented within Pulumi state.
The model for these depends on the implementation language of the component resource, and most commonly they are implemented as classes where the programming language supports that.
(view-resources)=
View resources represent a view of a resource that's created externally to Pulumi. These resources are created by a provider, as part of a custom resource, and represent a "view" of resources managed externally to Pulumi. These can e.g. be resources set up through OpenTofu, but as part of a Pulumi Program. Pulumi doesn't manage the lifecycle of this type of resource itself, but rather defers to the provider to do so.