TYPO3

Conceptually, TYPO3 consists of two parts: the frontend, visible to visitors, and the administrative backend. The frontend displays the web content. The backend is responsible for administration and managing content. The core functions of TYPO3 include user privileges and user roles, timed display control of content (show/hide content elements), a search function for static and dynamic content, search-engine friendly URLs, an automatic sitemap, multi-language capability for frontend and backend, and more.

Like most modern CMSes, TYPO3 follows the policy of separation of content and layout: The website content is stored in a relational database, while the page templates are stored on the file system. Therefore, both can be managed and updated separately.

TYPO3 defines various basic types of content data. Standard content elements are described as text, text with media, images, (plain) HTML, video etc. Various added types of content elements can be handled using extensions.

The fundamental content unit is a "page". Pages represent a URL in the frontend and are organized hierarchically in the backends' page tree. Standard pages serve as "containers" for one or multiple content elements. There are several added special page types, including:

• shortcuts (they show content from another page)
• mount points (that insert a part of the page tree at the mount point)
• external URLs
• system folders (to handle complex data such as registered users)

Internally, TYPO3 is managed by various PHP arrays. They contain all the information necessary to generate HTML code from the content stored in the database. This is achieved by a unique configuration language called TypoScript.

Designing and developing with TYPO3 is commonly based on the following elements, among others:

Page tree

Representation of all pages of a site, their structure and properties.

Constants

System-wide configuration parameters

Template

Since TYPO3 6, the system runs on the templating engine Fluid. Fluid combines HTML markup with conditions and control structures. It can be extended by custom view helpers written in PHP.

Until version 4.3, an HTML skeleton was used, with markers (e.g., ###MARKER###) and range markers, called subparts (e.g., <!-- ###CONTENT### Start --> … <!-- ###CONTENT### End -->); that were replaced by various content elements or served as a subtemplate. This template system can still be found in older extensions or installations.

TypoScript

TypoScript is a purely declarative configuration language. In Typoscript, configuration values are defined, which are parsed into a system-wide PHP array. TypoScript is object-based and organized in a tree-like structure.

Extensions

Added plug-ins to enable more functions. See Extensions.

PHP

TYPO3 CMS is written in PHP. Thus, most features can be modified or extended by experienced users. For example, the XCLASS mechanism allows classes and methods to be overwritten and extended. If available, hooks are preferred.

Extensions are the cornerstone in the internal architecture of TYPO3. A feature that was introduced with version 3.5 in 2003 is the Extension Manager, a control center managing all TYPO3 extensions. The division between the TYPO3 core and the extensions is an important concept which determined the development of TYPO3 in the past years. Extensions are designed in a way so they can supplement the core seamlessly. This means that a TYPO3 system will appear as a unit while actually being composed of the core application and a set of extensions providing various features.[13]

Diagram of the basic TYPO3 system architecture

They can be downloaded from the online repository (TER) directly from the backend, and are installed and updated with a few clicks. Every extension is identified by a unique extension key (for example, tt_news). Also, developers can share new or modified extensions by uploading them to the repository.[9]

Generally, extensions are written in PHP. The full command set of PHP 5.3 can be used (regarded the system requirements of the specific TYPO3 version), but TYPO3 also provides several library classes for better efficiency: Best known and most used is the piBase library class. With introduction of TYPO3 4.3 in 2009, piBase has been replaced (or extended) by the Extbase library, which is a modern, model–view–controller (MVC) based development framework. To ensure backward compatibility, both libraries can be used in the same TYPO3 installation. Extbase is a backport of some features of FLOW3, renamed Neos Flow, a general web application framework.[14]

A completely rewritten version (code-named "Phoenix") was originally planned as TYPO3 version 5.0. While working on this new release and analyzing the 10-year history and complexity of TYPO3 v4, the TYPO3 community decided to branch out version 5 as a completely separate product, one that wouldn't replace version 4 in the near future and as such needed to have its own name. Published as FLOW3, now renamed Neos Flow, it along with various other packages then served as the basis for the start of development of project Phoenix.[72]

In September 2012, the TYPO3 developers decided on the name for the new product, "TYPO3 Neos".[73] With TYPO3 Neos 1.0 alpha1, a public test version was released in late 2012.[74][75] In May 2015 the TYPO3 Association and the Neos team decided to go separate ways, with TYPO3 CMS remaining the only CMS product endorsed by the Association and the Neos team publishing Neos as a stand-alone CMS without any connection to the TYPO3 world.[76]

In January 2017, Neos 3.0 has been published, along with a new version of Flow framework and a name change of its configuration language from TypoScript2 to Fusion.[77]