How to Show Who's Online in Your Joomla Website
The Who’s Online module in Joomla indicates how many guest and registered (logged-in) users are on your site at any time. The module is a simple one, and if you chose to install the sample data that came along with your Joomla installation, it is enabled by default — just fill in what pages you want the module to appear on in the Menu Assignment pane on the module’s administration page.
You can configure the module to show the names of the current members logged on, if you want. Just select one of these options in the Module Parameters pane of the module’s administration page:
# of Guests / Members
You can also choose to enable the module’s Link feature by choosing either the Yes or No radio buttons in the Basic Options pane. Doing so will provide your site’s visitors with a link they can follow to view the profile or contact information of any of the site’s registered users who happen to be logged in during their visit.
A word to the wise: On high traffic sites the Who’s Online module can cause a lion’s share of headaches, as your Joomla site’s database is called upon each time the module loads on a page. The busier a Joomla site is, the longer its database table will be. This means longer page load times for anyone visiting a site.