So what is Emulation you ask?
Well, by Definition Emulation means: The act of one computer or processor acting like another.  So emulation is the act of mimicing or simulating a computer with another computer or program.  Emulation is all about preserving the gaming spirit and remembering those great days when those classic arcade games, 8-bit and 16-bit systems ruled!
 

So what's an Emulator?
An emulator is a program, software, or hardware that allows a computer to perform the functions of, or execute the programs designed for another type of computer or processor.  A computer emulator is a program which can mimic the behavior of another computer system.  For example, the ZSnes Emulator simulates the Snes's graphics and sound processing, the Snes's main cpu, joypad controls, layering, sprites, etc... and makes your computer "act" like the Snes system.

Put in simpler terms, it's just a program that makes your computer think and perform as if its an Nes, or an Snes, or a Sega Genesis, and so on...  Pretty cool huh?  Yea I thought so too my first time...  It's awesome.  And the best part of it is that almost all of it, is for free and completely legal.  None of that WareZ stuff.  Emulators are the results of hard working programmers or even normal people with some background in computer programming, compiling, coding, debugging, etc... and they should be respected.
 

Where can I get these Emulators?
Well, for starters you can get some of most popular and best emulators around, from my site, and I have links to where you can find emulators that aren't here.  Well the point is that you can get them almost anywhere on the Internet.
 

What are RoMs?
RoMs are the "games" for these different emulators.  Roms are just the files that contain whatever was stored in the original cartridge.  It's the the same thing as if you went to buy an Snes game, but it's just the file of it, without all that fancy covering.  You just load up the emulator and then load up the game through the emulator, and you are ready to experience emulation. **Note** You can't play Genesis roms on the Snes emulators, Nes roms on the Snes emulators, Game Boy roms on the Genesis emulators, and so forth, because all the different games are in different formats and the emulators won't recognize them unless they are meant for them.

For example the most common Snes games are in .fig, .smc, and .sfc formats.  Most common Sega Genesis games are in .smd and .bin formats.  The Nes games are usually in .nes formats.  So as you can see the Emulators will only recognize their own specific file formats.
 

Where can I get these RoMs?
They are everywhere!  I have many links to RoM sites and Message Boards in my RoM  Section...But since almost all games are for free, not everything is legal.  Check is this stuff legal? for more info about the matter.