You get used to it, I don't even see the code. All I see is a blond, brunette, redhead.”
Matrix code, also known as Matrix digital rain or sometimes green rain, is the computer code related to the Matrix franchise. The falling green code is a way of representing the activity of the virtual reality environment of the Matrix on screen. All three Matrix movies, as well as the spin-off Animatrix episodes, open with the code. It is considered a characteristic mark of the franchise, more or less like the opening crawl is for Star Wars.
In the films, a few people can understand what happens inside the Matrix by looking at the code on computer monitors. Operators from Zion, unable to enter into the Matrix, concentrate on ways to read the scrolling code, or "rain", and infer data from it such as the location of a person in The City, possible exits, and so forth. As the character Cypher explains in the first film, although they have translation software that allows a visual representation of the Construct, the programming of the Matrix contains too much information to analyse in this way, and must be viewed encoded.
The complex "Matrix code" of raining green characters and pictograms allows the Matrix program to be concisely represented and thus read more easily. The character Neo is the only human that can see the code of which avatars are composed while in the Matrix, and is therefore able to see their "true" digital form. By contrast, some programs are not seen as part of the green code, but as golden code (e.g., Seraph).
The code is characterized by green flashing reversed Roman and Japanese katakana characters and Arabic numerals, as well as pictorial symbols, such as a bull's head (as pictured at the end of the Matrix Revolutions title sequence), falling in a black screen while changing and fading. The effect resembles that of the older green screen displays, since the letters leave a fluorescent trace on the screen.
In The Matrix: Path of Neo game the player can press up on the d-pad (on the PlayStation 2 and Xbox version) and the "C" key on the PC Version, and the world would turn into this "code vision." A similar effect is seen when the game is paused. In the Matrix MMORPG, The Matrix Online, the world first loads with everything as green code, slowly fading into a more realistic view.
The creators of the Matrix claim the look was inspired by the Korean language credits at the end of the movie Tron.
No official version of the code's typeface actually used in the Matrix trilogy and in the website for the game Path of Neo has been released. Several imitations have been made.
Sound designer Dane A. Davis digitized raindrops against window panes to create the sound of the letters as they rotate and fall.
Though uncredited in the films, Simon Whiteley created the Matrix code. In an interview with CNet, he said that he scanned the characters from his wife's Japanese cookbooks, saying "I like to tell everybody that The Matrix's code is made out of Japanese sushi recipes".
In popular culture
Because of the popularity of the movies, the effect has become noted in itself and a part of pop culture. It has influenced other franchises and has been used in new-tech advertisements, TV spots, video-clips, posters and appeared in other high-tech topics, such as flash intros of cyberpunk related websites. There are several screensavers based on it, like XMatrix and GLMatrix found in the XScreenSaver collection.
- The code appears in some scenes in Code Lyoko.
- A horizontally-scrolling variation of the "rain" can be seen briefly in the 2001 film Swordfish, where a character creates digital encryption code. Movie producer Joel Silver was involved in both projects.
- There are t-shirts that feature the digital rain. In a scene from the film Goodbye Lenin, a character wears one despite the film taking place in 1991, nearly a decade before the first Matrix film came out. In a deleted scene for the film, the character wearing the shirt tells Alex (the main protagonist) about an idea he has for a film called Planet of the Forgotten about people kept in a computer simulation, and much of the main plot of the film is about Alex keeping his mother unaware of the collapse of the Berlin Wall (another form of altered reality).
- In the computer game Deus Ex, there is a cheat, known as 'may-tricks mode', which replaces all in-game textures with a constantly scrolling form of digital rain.
- In the Justice League Unlimited episode The Once And Future Thing: Part 2, a screen in Batman's control room features scrolling digital rain.
- At one point in the video for Skillet's song "Alien Youth", what looks to be the matrix code can be seen.
- In the 2001 computer game Independence War 2: Edge of Chaos a yellow code rain falls down on the menus in the matrix fashion, though it uses different characters.
- In the song "I'm still here" by John Rzeznik, a Matrix-like rain can be seen sometimes throughout the music video. The difference is that the music video's rain is a white color instead of the usual green.
- In 2007, World Wrestling Entertainment promoted the return of Chris Jericho with a viral marketing campaign using 15-second cryptic binary code videos, similar to the matrix digital rain. The videos contained hidden messages and biblical links hinting Jericho's return and were shown interrupting WWE broadcasts. 
- The 2007 version of Epcot's Spaceship Earth features the matrix code in the updated Tunnel of Facts and Figures in place of the earlier version's glowing lights.
- The vocations offices of several Latin-Rite Roman Catholic diocese have posters featuring a young cleric in a cassock holding a rosary posed to look like Neo, but the rain behind him reads the text of the Salve Regina, Ave Maria, and other prayers, while the poster as a whole is made to look like a movie advertisement, complete with credits. The diocese usually affixes their seal with office information.
Code similar to that in The Matrix can be seen in an earlier movie Alien (1979, directed by Ridley Scott). There is a scene where Captain Dallas is "talking" with Mother and the "Matrix code" can be seen (even the word 'matrix' is written in the Mother Program main menu screen). Another similarity is where Lt. Ripley (Sigourney Weaver) is seen looking at a monitor with a "green (matrix) code" and she is interpreting the code and understands that the transmission was no S.O.S. but a warning.
In the 1993 book Mindstar Rising by Peter F. Hamilton, in Chapter 20 the main character Greg Mandel vists friend Royan whose room is described in part: "One wall was covered from floor to ceiling in TV screens, not modern flatscreens but the antique glass vacuum tubes of the last century. They'd been taken out of their casing and stacked edge to edge. like bricks, in a metal frame. Some were showing channel programs, some relayed images from cameras dotted around the tower, others had reams of green script unfurling in a constant cascade from top to bottom."
In the 1996 movie Independence Day, a code scrolling effect very similar to that of the Matrix code can be seen on the cockpit monitors of the alien flying saucer that was captured by the U.S. government.
In his 1988 book The Mathematical Tourist: Snapshots of Modern Mathematics, Ivars Peterson writes about a very similar mathematical idea of cascading symbols representing an evolution of description of tautological possibilities.
- Joel Silver, interviewed in "Scrolls to Screen: A Brief History of Anime" featurette on The Animatrix DVD.
- Creator of The Matrix code reveals its mysterious origins – CNET, October 19, 2017
- Breaking the Code, November 19, 2007, WWE.com
- Official screensaver - Digital rain for both Mac OS 9 and Windows
- Guide to create the Matrix effect in Photoshop
- The Matrix Trilogy screensaver - unofficial, fan made screensaver simulating the digital rain
- Simple Matrix rain effect in PHP - A simple script that uses PHP to create the Matrix digital rain effect animation
- Matrix digital rain generator (PNG still-picture with PHP)
- 3D screensaver - another fan made of the digital rain screensaver in 3D for Windows
- Digital Rain using Microsoft Excel
- Digital Rain using VBA & Excel
- Digital Rain using HTML5/CSS3/JS
- Cmatrix, a command in Linux
- Ultimate Screensaver Collection - Bittorrent link to huge collection of digital rain screensavers for Windows, Macs, and Linux. (Some of the above referenced screensavers are included in this collection along with many others.)