General idea of X-Cart customization is that each change can be done as a separate module. Since module files are separate from the core, upgrade of X-Cart can be performed simply by replacing files. The same way, module can be upgarded just by replacing its own files.
To achieve such flexibility there are certain approaches to X-Cart customization and we are going to go through them in this section.
There is also the exercise book that gives you real-world tasks, so you could practice your X-Cart 5 programming skills.