tfenv is a versioning tool for managing multiple versions of Terraform across different environments such as development, testing, staging, and production. It allows users to easily upgrade or rollback to specific versions of Terraform as needed. The article provides step-by-step instructions on how to install, upgrade, switch, and uninstall Terraform versions using tfenv. Additionally, Spacelift is recommended for managing Terraform versioning, state, workflows, policies, configurations, and more.