Why is it important to add execute permissions to a shell script?

Adding execute permissions to a shell script is important because it allows the script to be run as a program. By default, new files do not have execute permissions, which means that even if the script contains valid commands, the operating system will not allow it to be executed. Without execute permissions, attempting to run the script will result in a "Permission denied" error. Granting execute permissions ensures that the script can be executed by the user or group specified, enabling the intended functionality of the script.