• char - 1 byte - is used to store a single character (ASCII) value

char Temp;    // Variable definition or declaration (letting compiler know we will need it in the future)
Temp = 25;    // Variable initialisation (assigning a value)
extern int my_var // Declaration. It tells the compiler that my_var is defined outside this file

Address of the variable

char a1 = 'A';
&a1                 // Gives you an address - memory location of the variable temp. Type is char* 
printf("%p\n", &a1) // %p - is the special format specifier for pointers