The document discusses infrastructure as code (IaC) and the tool Terraform. IaC allows infrastructure to be provisioned and managed using code and version control. This makes infrastructure reusable, testable, and maintainable. Terraform is an open-source IaC tool that uses declarative configuration files to manage cloud infrastructure in a cloud-agnostic way. It generates execution plans to show exactly what changes will be made before implementing them. This allows infrastructure to be created reproducibly.