I've seen the term used before and the 1st thing that came to mind was developing a library. Then I read this post on SO: http://stackoverflow.com/questions/7122192/creating-an-objective-c-api Along with this link about how to build a static library in ObjC for the iPhone: http://blog.stormyprods.com/2008/11/using-static-libraries-with-iphone-sdk.html If you do a Google search, the returns are about making custom classes. Q. what does API development mean? It seems that it means making custom classes and/or extending current classes more than anything to do with a static library because a static library is nothing more than code in a different form of storage. Also, does API development include documentation and is that standardized? I didn't see anything covering that. --- Post Merged, Apr 8, 2016 --- Here's a bit more on the subject: http://www.sitepoint.com/do-you-need-an-api/ Which seems to be geared towards web services more than iPhone Dev.