Can you explain the purpose and use of the require directive in the composer.json file?

The require directive in the composer.json file is used to specify the project's dependencies — libraries and their versions needed for the application to work.

Example:

{
  "require": {
    "monolog/monolog": "^2.0",
    "guzzlehttp/guzzle": "^7.0"
  }
}

This means that the project depends on the monolog/monolog package version 2.0 and above, but below 3.0, and guzzlehttp/guzzle version 7.0 and above. Composer will automatically download and include these libraries during installation, ensuring dependency management and compatibility.