Hi Esser - Whether you need a blog, feedback forms, an online shop, integrations with external web services, calendars, and much more ... extensions give you a wide range of flexibility to go beyond core functionality, growing your site hand-in-hand as your business and site grow. They are the ideal building block for creating complex online solutions.
There are more than 1,500 extensions available in the TYPO3 Extension Repository (TER) on TYPO3.org for you to browse and assess according to your needs. Download and install them directly with the TYPO3 backend Extension Manager. And TYPO3 is open source! You and your developers (or your TYPO3 service provider) can also create new, custom extensions to meet your specialised needs.
Fluid - TYPO3's next generation templating engine - is used for creating custom extension templates.
Fluid's approach to creating templates emphasizes simplicity, flexibility, extensibility, and easy of use. The syntax is XML-based and can be used in any Web IDE. With its ViewHelpers, Fluid can be extended by powerful functionality that fits custom web project needs.