Maintaining a WordPress website involves many tasks. First, minor tweaks like revising or publishing content, updating a plugin or finding and fixing broken links can be done when your WordPress website is live and does not require downtime. But more significant changes, like redesigning your website or switching servers, require downtime.
In that case, to avoid poor impressions, it is best to take it offline by putting your website into maintenance mode.
When a website is in maintenance mode, the URL displays a screen with a message regarding the state of your website. The message usually clarifies why the website is offline and estimates when it will be live again. As a result, it allows you to show a user-friendly notice to visitors instead of a broken website.