A lot of internet users now hear about the ability to update your own website all by yourself without waiting for a web designer to do the changes for you which of course will not be updated immediately.
This can be done for sure by using what we call Content Management System and there's a lot of them offering free software to install on your web hosting, assuming you have access to your cPanel on your web host and you'll get your website up and running in just few seconds.
Two of these free software had gain popularity over the internet and they are called WordPress and Joomla, actually they are so many like Drupal and Typo3, well I have not tried them to be fair.
So if both WordPress and Joomla are popular which one should consider when designing your website
1) In terms of usability
WordPress has more users since it does not require any web development knowledge, but it has fewer features than Joomla
2) In terms of adaptability
WordPress simply is another flavor of Blog where Joomla is a really advanced content management system, it can manage subscriptions for users and you can create what you call free or paid subscribers.
3) In terms of search engine optimization
WordPress is a search engine friendly and they rank high easily on Google but in Joomla you need to do some customization in order to get ranked in search engines.
4) In terms of scalability
Joomla is very flexible you can do anything with Joomla starting from designing a simple website up to more complex features on your websites, while WordPress on the other hand will work excellent if you intend to display content, update and add frequently where WordPress plug-ins can not be compared to Joomla.
5) In terms of integration
Joomla can really integrate easily with third party software, it has a powerful API that developers use to extend the software or integrate it with other systems.
6) In terms of using the admin area
WordPress has a very easy admin area, it's excellent for publishing content and that's it, Joomla is full of functionality and features like e-commerce (Shopping card), order management, inquiry management also document management..etc and that's why it's complicated and requires a learning curve.
Note: I'm an expert in WordPress, I really love it and I can help you to build your website Free , teach you WordPress and teach you Joomla.

