Extbase is a PHP-based framework for TYPO3. The templating engine Fluid makes sure that the user interface of the extension can be created easily and separately from the functionality (MVC).
Extbase ensures a clear separation between different concerns which simplifies maintenance. The modular design reduces the development time and associated costs for initial development and for adjustments. Extbase also lessens the burden on the developer when it comes to security-related and repetitive tasks like the validation of arguments, the persistence of data, and access to TypoScript and FlexForm settings. Developers can therefore focus on solving the problems of their clients much more efficiently.
Because of the modern architecture and the usage of up-to-date software development paradigms, using Extbase requires specific knowledge. Extension programmers must understand some concepts like Domain-Driven Design, whilst planning and modeling the extension more thoroughly before implementation. This has the advantage that the source code of the extension becomes better readable, more flexible and extensible.