Computers are the medium used to play interactive fiction. Computers come in different brands and models, and if a game is written for only one type of computer (e.g. Apple II), you won't be able to play that game without either an Apple II computer, or a program that emulates that computer (such a program is called an emulator).
Most interactive fiction games today are written with authoring systems that aren't targeted to a particular computer. Instead, they target a virtual machine. The released game is a story file, which isn't an executable. To play the game, you will need an appropriate interpreter program which emulates the virtual machine on your actual computer.
Detailed information about real-world computers is outside the focus of the IFWiki. Articles in this category will likely be very brief, possibly explain their historical relevance to IF, and provide links to more detailed information elsewhere.