Recommended · for beginners
Raspberry Pi - Resize the partition to fill the SD card
Why people recommend it
An early Raspberry Pi tutorial on growing the root partition to use the whole SD card on Debian images; one user reported trouble following it.
Watch for: Written for 2012 Debian images; may not match newer systems
In their words
You can find instructions on doing this here.
Steve Robillard on raspberrypi.stackexchange.com, Jun 2012. CC BY-SA.