How to format a hard drive for use on a PC or Mac computer

To format a hard drive before you start using it in Windows, use the Disk Management utility; on a Mac, use Disk Utility.

How to format an SD card and erase all of its data

You can format an SD card using Windows, Mac, and Android devices, and likely your digital camera too.
Ars Technica

Pick the right file system for your Mac’s internal or external storage

When you put a new hard drive in your Mac—or connect an external one using FireWire or USB—you need to decide how to partition the drive and what file system to ...