In order to get up and running with your Raspberry Pi 2 you will need the following additional hardware components:
MicroSD card
Micro USB power cable
Monitor—preferably HDMI
HDMI cable or 3.5mm to RCA AV cable
USB keyboard
USB mouse
Protective case—optional
Wi-Fi dongle or Ethernet cable
Many websites offer starter kits that include some of these components, and an existing monitor can be reused.
The eLinux website also provides a good guide to peripherals at http://elinux.org/RPi_VerifiedPeripherals.
Before we can power up and start using our Raspberry Pi, however, we need to install an operating system on a microSD card.