Terraform is an open-source infrastructure-as-code (IaC) tool that allows developers to provision, manage, and version cloud resources in a declarative manner. It supports multiple cloud providers, including AWS, Azure, and Google Cloud, enabling consistent infrastructure management across environments. Terraform's reusable modules simplify complex setups, while its state management ensures accurate resource tracking. It is widely used in DevOps for automating and scaling infrastructure deployments. Terraform's flexibility and multi-cloud support make it a key tool in modern cloud engineering.