I am reading about iOS programming and I bought the Programming iOS 4 book. There is a introductory part where among several things "Files" is mentioned. 

I don't understand how the source files is put together. You have a header file with function declarations, then you have a corresponding file with the function definitions.

Let say you have a Car.h and Car.m & Person.h and Person.m.

Now, if you want to use the Car in the Person class you would import only the Car.h file. How is this sufficient? I don't understand the sequence it put together and builds a program. (Not thinking about the technical stuff, just h/m files.)