Over the past summer, I’ve spent a lot of time working with e-commerce software Magento for several clients. Its biggest appeal is also its worst downside for developers: Every part of it is completely extensible without ever needing to touch the core code. That’s great, as long as you don’t look too closely at how that’s actually achieved. I’m not here to rant, though–with a little luck, I’ll save you some of the headaches I ran into when I was starting off.

Fact is, Magento can and probably will be overwhelming on your first time digging through the code, especially if you’re not familiar with the Zend Framework. But then, it does have more than 9,300 files before it’s even installed…

Almost everything you will need to deal with, whether you’re a designer or a developer, is in the /app folder.

/app/etc contains Magento’s basic configuration.

/app/code contains all of Magento’s code, split up by source [community, core or local], publisher, and module. All of the core Magento code is in /app/code/core/Mage. If you ever plan on upgrading, you probably shouldn’t change anything in that folder. If you install a Magento Connect extension, you’ll find the code for it in /app/code/community.

Within each module there are a bunch more More >