Learning Joomla! 3 Extension Development, 3rd Edition

Joomla 3 is the first of the major open source content management systems that was meant to be mobile friendly by default. Joomla uses object-oriented principles, is database agnostic, and has the best mix of functionality, extensibility, and user friendliness. Add to that the fact that Joomla is completely community driven, and you have a winning combination that is available to everyone, and is the perfect platform to build your own custom applications.