Different ways of compilations in android

Different compilations are used for android code

1. Compilation of complete code
$make
2. Compiling android kernel
$make bootimage
3. compiling system img
$make systemimage
4. compilation of an apk
open Android.mk of an apk
LOCAL_MODULE := xyz_module_name
$make xyz_module_name

5. mm is command to compile the indiviual modules . TO work this command first all the code should compile atleast once