What is the purpose of 'docker-compose.yml'?

The purpose of 'docker-compose.yml' is to define services, networks, and volumes for a multi-container Docker application. This configuration file allows users to specify how different containers should interact with one another, share resources, and connect through defined networks. By using this YAML file, developers can organize complex applications that are built from multiple services, each potentially running its own container.

For example, if an application consists of a web server, a database, and a cache service, 'docker-compose.yml' can be used to define each of these components as services, set up how they communicate, and manage their persistent data through volumes. This streamlines the deployment and orchestration of multi-container applications, facilitating easier management and scalability.

The other options refer to functions not addressed by the 'docker-compose.yml' file, such as launching single containers, managing Docker images, or directly configuring local storage settings, which can be handled by other Docker commands or files.