1
a=$(b) "a" is pointer on "b"
2
x=y;y=z;a=$($(x)) Using pointers, a is equal to 'z'
3
a:=$(b) "a" is equivalent to "b"
5
b:=$(a:.o=.c) Changes all extensions from ".o" to ".c"
7
$(patsubst %.o,%.c,$a) Some
8
$(filter %.o $files) Only thoose files which have ".o" extension
9
$(wildcard *.o) All files in current directory with ".o" extension