A website is an operational system, not a one-time design file. Software updates, security monitoring, content changes, backups and performance reviews all continue after the initial launch.
What to consider
Maintenance priorities depend on the platform. WordPress sites may need frequent plugin and theme updates, while custom applications require dependency management, server monitoring and release processes.
Create a maintenance schedule, assign ownership and test key customer actions regularly. A broken contact form or expired certificate can cost business even when the homepage appears normal.