Object-oriented programming, which has been around since PHP 5 and has many restrictions compared to other programming languages, is a relatively recent development.  In Magento 1, the Mage class is used to implement and call nearly all objects. The Mage class is swapped out in Magento 2 by Object Manager. By establishing close connections between three patterns—object management, dependency injection, and plugins—this helps to address some of the issues that arise when you instantiate arguments.  Use of standard PHP classes is not prohibited in Magento 2. To leverage the sophisticated object features of Magento 2, however, there will be need to employ  the object manager (automated function Object() { [native code] } dependency injection, object proxying, and so on).