Super Metroid is the third game in the Metroid series, released for the SNES in 1994. Currently, it is the most widely-hacked Metroid game, and has the most resources available to help hackers. All information here relates to the specific unheaderedROM: “Super Metroid (JU) [!].smc”, which should be 3,145,728 bytes in size and have CRC D63ED5F8, sha1sum DA957F0D63D14CB441D215462904C4FA8519C613, and md5sum 21f3e98df4780ee1c667b84e57d88675; if your rom has a different checksum, then it is not a clean unheadered vanilla ROM, and you should try to acquire a new one. If you do not know how to verify your ROM's checksum, try opening the ROM in snes9x or use something like QuickHash or Microsoft's Checksum Tool. For information related to patching this ROM please check Patching a ROM or The HOWTO on the main site.
For editing Super Metroid, SMILE 2.5 is the primary tool used; a more updated version Parlor is available, but is unstable. Most information here will be with 2.5. SMILE has two derivatives currently in production, SMILE JX created by JAM and SMILE RF by Scyzer.
A list of guides created by the community, from manuals on the tools themselves to advanced guides relating to ASM, its all here.
Manuals of the workings of all the editors and utilities available to you, detailing all their functions.
These guides cover all the basic things around editing Metroid, as well as serving as a good starting point for learning how to get into Metroid hacking!
These guides assume you have a good basic knowledge about editing Super Metroid already, you should probably be comfortable with using SMILE by now and be moving onto using tools like a hex editor.
These guides could be pretty complex, you should probably be comfortable with assembly by now.
This segment is reserved for technical information on Super Metroid, to be used as reference material for hackers, or for the curious wanting to know what makes Samus tick, or possibly you are interested in making a fan game and want to know how Super Metroid does things!
Data maps of ARAM, VRAM, RAM, and ROM are here.