Magento is an Open-Source e-Commerce web application built upon the Zend Framework. It uses the Entity-attribute-value (EAV) database model to store data, and developers can modify the core code and add features and functionality by installing extensions from the Magento Connect marketplace.
Varien, the company owning Magento, formerly worked with osCommerce. They originally planned to fork osCommerce but later decided to rewrite it as Magento.
While Magento Community Edition is Open-Source software that can be downloaded for free, businesses using Community Edition to run their stores will want to have access to their own Magento experts, since Magento does not provide technical support for this software. Answers to many technical questions are available on ouruser forum.
Small businesses that prefer to have access to technical support and a more comprehensive feature set should consider Magento Go, a “commerce in the cloud” solution. Mid-large size businesses that need support, additional features and our best performance should consider Magento Enterprise Edition.