What is the purpose of Docker Compose's "depends_on" directive, and how can it be utilized to define service dependencies?

The "depends_on" directive in a Docker Compose file is used to define service dependencies within a multi-container application. While it doesn't guarantee service readiness, it influences the order in which services are started and stopped. So, when one service depends on another using "depends_on" Docker Compose starts the services in the specified order.

This directive can be particularly useful when a service relies on another service, such as a web application depending on a database. However, it's important to note that "depends_on" doesn't wait for a service to be fully operational before starting dependent services.