A custom script is a piece of code that can be written to perform a specific task or automate a process. A custom script can be used to gather patch information on a specific server by querying the server's operating system, registry, or patch management software and retrieving the relevant data. A custom script can be more flexible and efficient than other methods, such as Event Viewer, SCAP software, or CI/CD, which may not provide the exact information needed or may require additional steps or tools.