SEF (Search Engine Friendly) urls are built-in in Joomla. Additionally, Joomla allows you to explicitly set the meta description and the meta keywords of any page – which also props up your SEO standings. In short, Joomla allows you to do the basic SEO yourself – instead of paying top dollars for a consultant or a 3rd party company to do it for you.
Joomla provides large number of plugins and modules to increase the performance and functionality of websites as per the requirement which makes it highly scable CMS.
In most cases, whatever functionality you can think of already exists in Joomla’s huge extensions library. In many cases, Joomla’s extensions are free. Paid Joomla extensions are priced very reasonably.