Rufus is a boot USB maker utility, that helps format and create bootable USB flash drives, such as USB keys/pendrives, memory sticks, etc. It can be especially useful for cases where you need to create USB installation media from bootable ISOs (Windows, Linux, UEFI, etc.), to work on a system that doesn't have an OS installed, to flash a BIOS or other firmware from DOS or when you need to run a low-level utility.
If you ever wondered how to boot from an NTFS partition in order to install a Windows ISO, Rufus is the answer. Simply select your Windows ISO, set the "partition scheme" to "GPT partition scheme", "Target system" to "UEFI (non CSM)", and select "NTFS" as file system. This info is from people who have a UEFI board, if you have legacy BIOS, select "MBR" and "BIOS (or UEFI-CSM)". (To check if you have UEFI or Legecy BIOS, simply open "Run" from the Start menu or click on windows and R buttons toghter on your keyboard, enter "msinfo32", and in "Item" column look for BIOS Mode)
Non exhaustive list of ISOs Rufus is known to work with:
Arch Linux, Archbang, BartPE/pebuilder, CentOS, Damn Small Linux, Debian, Fedora, FreeDOS, FreeNAS, Gentoo, GParted, gNewSense, Hiren's Boot CD, LiveXP, Knoppix, KolibriOS, Kubuntu, Linux Mint, NT Password Registry Editor, Parted Magic, Partition Wizard, Raspbian, ReactOS, Red Hat, rEFInd, Slackware, Super Grub2 Disk, Tails, Trinity Rescue Kit, Ubuntu, Ultimate Boot CD, Windows XP (SP2+), Windows Vista, Windows Server 2008, Windows 7,Windows 8, Windows 8.1, Windows Server 2012, Windows 10, Windows Server 2016