Macros is similar to functions but it is a text replacement .. Pointers is a variables that been created by user to point into an address of specific variable and you can declare the pointer by the type of variable (for ex. pointer to integer, pointer to char). pointers are used to pass the addresses of variables inested of passing the variable. .. the memory we can say we have a two memory Ram and EEPROM the EEPROM is the fixed data memory that it store the Global and static variables while the Ram stores the local variables and temporary variables .