This tutorial assumes you are already logged in to your Joomla admin panel.
Setting the site to offline allows only administrators to access it. This is useful for editing the site when you don't want other people to see it.
1) Click Site.
2) Then Global Configuration.
3) Next to Site Offline, click Yes.
At this point, you can also edit your offline message which will be displayed to the user on the login page.
4) Click Save.
Now that our site is offline, only administrators will be able to log in. Let's go to our site.
5) Click Preview.
This is the page that will be displayed with your site logo, name and offline message.
Let's log in as administrator.
6) Type your username.
7) Enter your password.
8) Check Remember Me if you would like to be logged in automatically from now on.
9) Click Login.
You can now browse your site and make any necessary changes.
When you are finished, make sure to enable your site again. Let's do that now.
Return to your admin panel.
10) Go to the Global Configuration options.
11) Click No next to Site Offline.
12) Click Save.
That's it! You now know how to set your site to offline mode in Joomla.