[Skullmeat]

What is an emulator?
An emulator is hardware or software that enables one computer system (called the host) to behave like another computer system (called the guest). An emulator typically enables the host system to run software or use peripheral devices designed for the guest system. Emulation refers to the ability of a computer program in an electronic device to emulate (or imitate) another program or device. Most common is a console emulator. Video game console emulators are programs that allow a personal computer or video game console to emulate another video game console. They are most often used to play older 1980s-era video games on 2010s-era personal computers and more contemporary video game consoles. They are also used to translate games into other languages, to modify existing games, and in the development process of "home brew" DIY demos and in the creation of new games for older systems. The Internet has helped in the spread of console emulators, as most - if not all - would be unavailable for sale in retail outlets. Examples of console emulators that have been released in the last 2 decades are: RPCS3, Dolphin, PCSX2, PPSSPP, Zsnes, Kega Fusion, Desmume, Epsxe, Project64, Visual Boy Advance, NullDC and Nestopia.

The Basics
In most cases, there are various common elements to all emulators, and their use.

ROMS - A copy (dump) of a game. There are many formats.

BIOS - Basic Input Output System. Some emulators (PCSX2, ePSXe) need a bios dump to operate. They are not included with emulators because they are proprietary software.

Basic Emulator Operation
For most emulators, there a few basic configuration options you will want to know about to get playing.

The Main emulation window - The main menu of the emulator. On start, they wont have a game loaded, so they will be blank. In this example the window includes several drop-down menus.



Here we see File, Emulation, Input, Sound, Video, Cheat, Netplay, and Help

Before we can begin playing, we need to load a rom. In most emulators you will use "File > Open/Load"



The game will begin.



While the game is playable at this point, we haven't done any configuration to the emulator, and have all the defaults. The screen is small, and we are stuck on the default controls.

Input > Configure



Here you can set keys or use controllers and joysticks.

Video and sound settings can be changed in much the same way: Video > Configuration; Sound > Settings





Plugins
Plugins can add extra features and functionality to your emulator. Generally there are 3 types: Sound, Video and Input. Unfortunately our example, Snes9x does not support plugins. I will cover them in detail later.

[Psi]

Thanks for this. :^)
I remember my hype when I managed to get my first nintendo emulator working!

[mothered]

A "basic" guide? Probably one of the best elaborated tutorials (on this topic) I've read.

Good work.

[Drako]

Quite the elaborate thread @Skullmeat . Good work, and definitely test out some of the emulators listed.

[Skullmeat]

By basic, I meant generic. I plan to do more on specific ones as well, like mame, which has a huge amount of features.

[Kyaa]

This guide makes me want to start playing games.