In this chapter, we explored most of the system-level libraries that OpenCart provides. Explore most of the extra code used in the featured product module, because of which you are now able to know the code flow of the OpenCart module. Likewise, we created a new shipping module that shows the shipping cost depending on the total cost purchased by cloning weight-based shipping. Similarly, we discussed the payment module of OpenCart and the ways to clone it. With this, you are now able to start coding with OpenCart extensions (Modules, Payment, and Shipping). In the next chapter, you will learn how to create custom pages and write the code required to perform the CRUD functionality.