When the Page Cache Plugin is enabled website pages will load faster without having to change the plugin's default settings.
For this reason we recommend that you enable the Page Cache Plugin.
But not if you are administering an eCommerce website.
Reason: enabling the Page Cache Plugin for an eCommerce website will prevent features like the shopping cart from working.
How Page Cache works
When the Page Cache Plugin is enabled, website pages will
"be cached and whenever they're requested again, the cached page will be served, rather than it being generated by Joomla from the information in the database. The cached page will continue to be served until it's expired – as defined by the Cache Time parameter in the ... Global Configuration - System tab - Cache Settings. "
Source: Joomla! Documentation.
How to enable the Page Cache Plugin
Select the Plugins button in the Site Panel of your website's Home Dashboard to browse installed Plugins.
If the Plugin is disabled (grey circle) then you can enable it by toggling the button (green tick).
The image below shows the Page Cache Plugin when it is enabled.
Click the name of the plugin to review its settings.
How to clear the Cache
Select Clear Cache in the Maintenance Panel of your website's System Dashboard.
Then click the Delete All button to clear the Cache.