The CPU load depends upon the amount of time a server spends executing a script each time a visitor opens a webpage on a certain script-driven website. Static HTML sites use barely any CPU time, but this isn't so with the much more sophisticated and functional scripts, which use a database and display dynamic content. The more customers open this sort of a website, the more load shall be produced on the server and if the database is big, the MySQL server shall be loaded too. An illustration of what may cause high load is an online store with a huge number of products. If it's popular, many people will be visiting it all at once and if they search for items, the entire database which contains all the products shall also be continuously accessed by the script, resulting in high load. In this light, having CPU and MySQL load statistics will give you an idea of how the site is doing, if it has to be optimized or if you just need a more potent web hosting solution - if the Internet site is extremely popular and the current setup can't deal with the load.