The Raspberry Pi requires the operating system to be loaded onto an SD card before it will start up. The easiest way to set up the SD card is to use NOOBS; you may find that you can buy an SD card with NOOBS already loaded on it.
NOOBS provides an initial start menu providing options to install several of the available operating systems onto your SD card.
Since NOOBS creates a RECOVERY Partition to keep the original installation images, a 4 GB SD card or larger is recommended. You will also need an SD card reader (experience has shown that some built-in card readers can cause issues, so an external USB type reader is recommended).
If you are using an SD card that you have used previously, ...