a pointer is an memory location in which it holds a particular ADDRESS of a particular data type. and mean while through the ADDRESS it will point to that corresponding value in that data typed variable.
DECLARATION OF A POINTER VARIABLE :
 int *pointer_variable;

for eg:
 int a=45;  //line 1
 int *b; // line 2
 b=&a; //line 3
 printf("%d\n",*b); //line 4

explanation:

line 1 :
       consider let address of the location 'a' be 1000, which contains a value 45 of integer data type.
line 2 :
        *b , represents the integer pointer which can hold an integer variable address. 
line 3 :
        when we take any variable such as int a or int c etc, when we call as 'a' we will refer to the content inside 'a' (for  eg.),in the same way as in the above coding *b is given . but b=&a; this means when we call 'b' the content (ie) the address of variable 'a', and that 'b' will be pointing indirectly the value of 'a' through the 'a's address.
line 4 :
         when we want to refer to that pointed value we must give as  *pointer_variable & here *b when you give the same 45 will get printed.




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