Arduino Port operation

Type of ports in Atmega328p;
Digital and Analog

DIGITAL PORTS 

PORTD : ( PD0 to PD7) 

Pin No : PD0-:( Pin 0 to Pin 7)

example :  PD2 = Pin 2 ;

DDRD = DDRD | B11111100;  // this is safer as it sets pins 2 to 7 as outputs
                   // without changing the value of pins 0 & 1, which are RX & TX 

PORTB : ( PB0 to PB5)

Pin No : PB0-5 : Pin 8 to Pin 13

BV=Bit Value.

PORTB |= _BV(PB5);

/* set bit 0 using _BV() */
PORTB |= _BV(PB5);

/* set bit 0 using shift */
a |= (1<<0);