In brief, Magento is an open source using PHP scripting language on Zend Framework. First introduced by Varien in 2007, Magento has continuously developed into various products and versions. Currently, it becomes one of the leading open-source platforms which offers almost all features and tools to build an ecommerce website.
Take Shoping Cart El|te for an example; is a fully hosted e-commerce solutions that will solve all your daily problems under one roof. They are not the largest platform around, but that's why they have reasonably priced packages and they serve business ranging from startups to enterprise solutions.