What is cache used for? in JOOMLA A Cache is a collection of data duplicating original values stored elsewhere or computed earlier, where the original data is expensive to fetch (due to slow slow access time) or to compute, relative to the cost of reading the cache. In other words, a cache is a temporary storage area where frequently accessed data can be stored for rapid access. Once the data is stored in the cache, future use can be made by accessing the cached copy rather than re-fetching or recomputing the original data, so that the average access time is lower. What does this mean in terms of Joomla? Instead of hitting your MySql database with same queries over and over again, your data is stored to a local storage (in the Joomla cache directory) and retrieved from there, instead of from the database. This means that your database will perform better, and your website will feel faster, and be able to support more simultaneous users. Activitating the Joomla Cache in joomla1.5 is quite straight forward. From the Global Configuration, click on System Tab, and on the right hand side there is the Cache Settings section. Click Yes on Cache Settings, and don't forget to put a "reasonable" amount in minutes (60 minutes should be quite good for most websites). Once you press Apply, Caching will be enabled.