What if this is not enough for my needs?

The day will come where all the APIs offered by Titanium won't be able to fulfill one specific need. Specific as it may be, it might prove vital for your business. Titanium allows more experienced developers to develop extension modules. The name says it all; extension modules extend the capabilities of Titanium while keeping the compatibility with the existing JavaScript code.

This is interesting because some platforms would require you to rewrite the entire application in their respective language (objective C or Java), just to have access to one specific feature of the platform.

Module developers can also hope to recoup their investment by distributing their modules on the Appcelerator marketplace, where other developers can download existing modules (for free or for a fee).