Describe the concept of 'resource' in Terraform.

In Terraform, a resource refers specifically to a block within the configuration that represents a single infrastructure object. This can include various types of infrastructure components such as virtual machines, storage accounts, network interfaces, load balancers, and more. Each resource block contains specific arguments that define its properties and configuration settings, allowing users to specify how that infrastructure should be provisioned and managed.

The key aspect of using resources in Terraform is that they are declarative; the user states what they want, and Terraform automatically handles the creation, updating, and deletion of those infrastructure components based on the defined configuration. The resources are fundamental to how Terraform operates, enabling the management of cloud services and infrastructure as code.

Understanding resources is crucial for effectively utilizing Terraform, as they are the primary units of work. Each resource block can interact and depend upon others, facilitating complex infrastructure setups through clear and concise configurations.