Joomla 1.5

History: -

It was released on January 22, 2008. The last release of this version was 1.5.26 on March 27, 2012. It was first version to attain long term support (LTS).
LTS versions are released each three major or minor releases and are supported until three months after the next LTS version is released

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Some Features: -

* Model View Controller: It was implemented in in Joomla! 1.5 for separating out logic, data and view of data.
* Template positions: The positions used in a template are now declared in templateDetails.xml.
* It has completely database driven site engines.
* News, products, or services sections are fully editable and manageable in Joomla!1.5.
* Topics sections can be added to by contributing Authors.
* It has fully customizable layouts including left, center, and right Menu boxes.
* Browser uploads images to your own library to use anywhere in the site.
* It provides Dynamic Forum/Poll/Voting booth for on-the-spot results.
* It runs on Linux, FreeBSD, MacOSX server, Solaris, and AIX.

Joomla 2.5

History:  -

It was released on January 24, 2012. This version is also a long term support (LTS) release. It was the first version to run on other databases besides MySQL. It has a host of new features including new search functionality, multi-database support, and update notification.

Key Features: -

* The new built-in feature of automated notification of Joomla! core and extension updates simplifies site maintenance and management of updates.
* Smart research option offers a faster, more user-friendly search experience for your visitors.
* Multi Database support helps to run the Joomla! CMS on many different databases, not just MySQL and MySQLi. This facilitates integration and update management processes.
* CAPTCHA uses scrambled text to prevent robotic spammers from submitting forms. Joomla 2.5 gains an API that lets you use CAPTCHAs in your forms.
* It helps to link new menus with module.
* You can use the Images and URL Fields to create Simple Standardized Layouts.
* It gives Greater Flexibility Filtering by Category in Article Manager.

Joomla 3.0

Coming next.....

Joomla 3.0 is scheduled to be released in September 2012. With this upcoming release lets look at what we can expect:

* It will provide new administrator backend and frontend design for better user experience.
* It will introduce core JUI library (Joomla User Interface). This will mostly be for component developers.
* Joomla 3.0 Default Template.