====== What Is gPXE? in Brief ======
gPXE is a boot-loader: a program that allows your computer to load either another boot-loader or your Operating System.  gPXE, however, is a very special kind of boot-loader that allows the computer to boot via a network, rather than a disk.  gPXE is the direct descendant of Etherboot; both are part of the Etherboot project, though Etherboot is no longer maintained.

====== Download Protocols ======
gPXE features several download protocols:
|TFTP| |
|NFS|Not by default|
|HTTP| |
|HTTPS|Not by default|
|FTP|Not by default|
|TFTM|Not by default|
|SLAM|Not by default|
|FSP|Not by default|

====== SAN-Boot Protocols ======
gPXE features two SAN-booting technologies:
|iSCSI|
|AoE|

====== Name Resolution Protocols ======
gPXE features name resolution protocols:
|DNS| |
|NMB|Not by default|

====== Booting Protocols ======
gPXE is a boot-loader that is capable of booting programs of several different formats:
|NBI (Network Boot Image)| |
|ELF| |
|FreeBSD Kernel| |
|Multiboot Specification-Conformant Image| |
|a.out| |
|WinCE| |
|PXE| |
|gPXE Script| |
|Linux bzImage (Kernel)| |
|COMBOOT/COM32| Not COM32R (Syslinux v4.00+); Use Syslinux 3.86 |
|EFI|Only Applicable on EFI Platform|

====== gPXE Shell ======
gPXE has a command-line interface (CLI), also called a shell, which allows you some manual control over what gPXE does.  Shell commands can be grouped together, one per line, into a file called a script.  In order for a script to be recognized by gPXE as a bootable image, you must put the following as the first line in the script:
  #!gpxe
Some of the command categories are:
|Automatic Booting|
|Non-Volatile Option Storage (NVO)|
|Option Configuration|
|Network Interface Management|
|Network Routing Table Management|
|Bootable Image Management|
|DHCP Configuration|
|SAN-Booting|

====== gPXE Formats ======
===== The Prefix =====
In order to allow a variety of methods for loading and running gPXE, the core of the program is prefixed by another program which is specific to a particular booting scenario or bootable media.  These different prefices are:
|ROM|For flashing gPXE onto a chip or as a loadable module from BIOS|
|PXE|TODO|
|KPXE|For loading gPXE from a PXE boot-loader via a network|
|ELF|TODO|
|ELFD|TODO|
|LMELF|TODO|
|LMELFD|TODO|
|LKRN|For loading gPXE as a pseudo-"Linux Kernel"-format file in a compliant boot-loader (LILO, SYSLINUX, EXTLINUX, ISOLINUX, PXELINUX, GRUB, etc.)|
|bImage|TODO|
|DSK|For loading gPXE from a floppy disk with no filesystem on it|
|NBI|For loading gPXE from a PXE boot-loader via a network|
|HD|For loading gPXE from a hard disk drive with no filesystem(s) on it|
|RAW|TODO|
|COM|For loading gPXE from a DOS prompt (Jan-7-2009: Broken)|
|EXE|For loading gPXE from a DOS prompt (Jan-7-2009: Broken)|
Each of these different formats for gPXE are available as compressed or uncompressed.

===== The Drivers =====
gPXE can be compiled to contain network interface drivers in three different ways:
|A Single Network Interface Driver|make bin/eepro100.lkrn; make bin/VVVVDDDD.lkrn|
|All Network Interface Drivers|make bin/gpxe.lkrn|
|A Single Driver that Uses the Network Interface's Built-In UNDI|make bin/undionly.lkrn|