The DevOps movement has introduced the concept of Infrastructure as Code, which allows defining infrastructure in specially formatted files and automating its creation or modification using automation tools. Atlas CLI is a command line tool that helps manage database schemas by keeping a representation of the schema in a file, allowing for automated updates based on a definition file. To use Atlas CLI, one needs to create a PlanetScale account, install and configure the PlanetScale CLI and Atlas CLI, and set up a new database with a specific connection string. The tool generates a schema definition file that can be modified and applied using the `atlas schema apply` command. This approach allows for version control of database schemas, providing accountability and historical references to track changes over time. However, when used with PlanetScale, it requires use on a non-production branch due to disabled DDL on production branches.