Magento’s Architecture

Magento is built on top of the Zend Framework, ensuring that the code base will be secure and scalable. The reasons for choosing the Zend Framework are many, but at a basic level the Zend Framework provides an object-oriented library of code with a committed company standing behind it. Using this framework, Magento was built with 3 central tenets in mind.
1. Flexibility: We believe each solution should be as unique as the business behind it. Magento‘s code allows for seamless customizations.
2. Upgradeable: By separating the core code from community and local customizations, Magento can be easily customized without losing the ability to upgrade.
3. Speed and Security: The coding standards used by the developers follow best practices to maximize the efficiency of the software and provide a secure online storefront.
In this chapter we will introduce key concepts and terminologies of Magento. Even if you won‘t be developing or designing for Magento these concepts and terminologies will help as you set up your own online store.

Core
The core of Magento contains all the functionality included in the downloaded version. The core code is a collection of modules developed or certified by the Magento core development team. Editing core files is not recommended and will disable the ability to upgrade Magento in the future.
Local
Local extensions are customizations of Magento which reside only on a user‘s local copy. These extensions will be placed in a local folder, so that they do not interfere with upgrades to the core code, and in order to differentiate them from community contributions. There are different types of extensions, which we will get into in a moment, but they will all reside in the same directory. Local extensions function just as core code does, only the directory is different

Community
Community contributions are just that, and when downloaded will reside in the community folder. Just like local extensions, by keeping them separate from the core code Magento store owners are able to enjoy the additional functionality without compromising the ability to upgrade to future Magento versions.

Extensions
In short, extensions are exactly what they sound like. One or more files packaged together to extend the functionality of Magento. Strict terms and conditions prohibit extensions from modifying the core code, ensuring that any extended functionality doesn‘t prohibit you from upgrading when a new version of Magento is released. Extensions can be installed from the admin panel, or downloaded from Magento Connect. These processes will both be covered later in the book, but let‘s look at the three types of extensions. There are three types of extensions, and they will reside in one of the two locations described above. There are 3 main types of Extensions.

Modules
A module is an extension which extends the features and functionality of Magento. You are probably familiar with the idea of modules from other software, but if not, some concrete examples of modules would be additional payment gateway integrations, or a featured items promotional tool.