A program is a set of code that completes a given task. Source code is the original code that the given program is written in, meaning specifically that the code isn't compiled. For example, the Android Open Source Project. The Android Open Source Project is a way if giving source code for everybody else to use. This is managed in git through Github, and you can build the source code for your device and then compile it into a zip file. I have no idea what object code is. Executable code I would assume is compiled code that can be worked with by the computer and ran. Executable code is in a few different formats throughout different Operating Systems. These files exist as .exe, .jar, bat files in Windos and in Mac OS X has .dmg executable files. Linux has meny, many different executable files, such as .run, .jar, and through the terminal, .zip and .bz2 files can be extracted and ran.