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In software development, the yo-yo problem is an anti-pattern that occurs when a programmer has to read and understand a program whose inheritance graph is so long and complicated that the programmer has to keep flipping between many different class definitions in order to follow the control flow of the program. It often happens in object-oriented programming. The term comes from comparing the bouncing attention of the programmer to the up-down movement of a toy yo-yo. Taenzer, Ganti, and Podar described the problem by name, explaining: "Often we get the feeling of riding a yoyo when we try to understand one of these message trees."

Most practices of object-oriented programming recommend keeping the inheritance graph as shallow as possible, in part to avoid this problem. The use of composition instead of inheritance is also strongly preferred, although this still requires that a programmer keep multiple class definitions in mind at once.

More generally, the yo-yo problem can also refer to any situation where a person must keep flipping between different sources of information in order to understand a concept.

Object-oriented design techniques such as documenting layers of the inheritance hierarchy can reduce the effect of this problem, as they collect in one place the information that the programmer is required to understand.

Rolling coal (also spelled rollin' coal) is the practice of modifying a diesel engine to emit large amounts of black or grey sooty exhaust fumes—diesel fuel that has not undergone complete combustion.

Rolling coal is a form of anti-environmentalism. Such modifications may include the intentional removal of the particulate filter. Practitioners often additionally modify their vehicles by installing smoke switches, large exhausts, and smoke stacks. Modifications to a vehicle to enable rolling coal may cost from US$200 to US$5,000.

In information security, a confused deputy is a computer program that is tricked by another program (with fewer privileges or less rights) into misusing its authority on the system. It is a specific type of privilege escalation. The confused deputy problem is often cited as an example of why capability-based security is important.

Capability systems protect against the confused deputy problem, whereas access-control list–based systems do not.

Far Cry is a 2004 first-person shooter game developed by Crytek and published by Ubisoft. It is the first installment in the Far Cry franchise. Set on a mysterious tropical archipelago, the game follows Jack Carver, a former American special operations forces operative, as he searches for journalist Valerie Constantine, who accompanied him to the islands but went missing after their boat was destroyed by mercenaries. As Jack explores the islands, he begins to discover the horrific genetic experiments being conducted on the local wildlife and must confront the mad scientist behind them.

The game was the first to use Crytek's CryEngine, and was designed as an open-ended first-person shooter, though it lacks most of the freedom its successors would offer to the player. While players can freely explore the game's world like in later Far Cry titles, they are most often discouraged from doing so due to the linear structure of missions and the lack of side content. Despite this, the gameplay formula established in Far Cry—placing the player in a foreign environment occupied by enemy forces where they must use various weapons and tools, as well as their surroundings to overcome any threat—would prove essential in defining the series' identity going forward.

Far Cry was released for Microsoft Windows in March 2004 to generally positive reviews, being praised for its visuals, gameplay mechanics, and the level of freedom given to players. The game was also a commercial success, selling over 730,000 units within four months of release and over 2.5 million units in its lifetime. The success of Far Cry led to a series of standalone sequels developed by Ubisoft, starting with Far Cry 2 in 2008. A remake of the game with a different storyline and new mechanics, Far Cry Instincts, was released for the Xbox in 2005, and for the Xbox 360 in 2006 as part of the Far Cry Instincts: Predator compilation. A loose film adaptation was released in 2008. The original version of Far Cry, updated with HD graphics, was re-released under the title Far Cry Classic for the PlayStation 3 and Xbox 360 in 2014.

Hotelling's law is an observation in economics that in many markets it is rational for producers to make their products as similar as possible. This is also referred to as the principle of minimum differentiation as well as Hotelling's linear city model. The observation was made by Harold Hotelling (1895–1973) in the article "Stability in Competition" in Economic Journal in 1929.

The opposing phenomenon is product differentiation, which is usually considered to be a business advantage if executed properly.

Yan Tan Tethera or yan-tan-tethera is a sheep-counting system traditionally used by shepherds in Northern England and some other parts of Britain. The words are numbers taken from Brythonic Celtic languages such as Cumbric which had died out in most of Northern England by the sixth century, but they were commonly used for sheep counting and counting stitches in knitting until the Industrial Revolution, especially in the fells of the Lake District. Though most of these number systems fell out of use by the turn of the twentieth century, some are still in use.

Satellite babies (also called Satellite Children) refer to immigrants’ children who are temporarily sent back to their home country by their parents to be reared by extended family. Typically, the satellite babies are born in the host country and sent back as infants, returning to their parents in time to start schooling or when their parents have established financial stability. Research and media articles on satellite babies have predominantly focused on the topic from a Chinese-American context. Satellite babies have become more prevalent in recent decades due to globalisation, prompting researchers and social workers to raise concerns about the psychological impacts of repeated attachment disruptions and acculturation associated with satellite babies.

A Kensington Security Slot (also called a K-Slot or Kensington lock) is part of an anti-theft system designed in the early 1990s and patented by Kryptonite in 1999–2000, assigned to Schlage in 2002, and since 2005 owned and marketed by Kensington Computer Products Group, a division of ACCO Brands.

The Abelian sandpile model, also known as the Bak–Tang–Wiesenfeld model, was the first discovered example of a dynamical system displaying self-organized criticality. It was introduced by Per Bak, Chao Tang and Kurt Wiesenfeld in a 1987 paper.

The model is a cellular automaton. In its original formulation, each site on a finite grid has an associated value that corresponds to the slope of the pile. This slope builds up as "grains of sand" (or "chips") are randomly placed onto the pile, until the slope exceeds a specific threshold value at which time that site collapses transferring sand into the adjacent sites, increasing their slope. Bak, Tang, and Wiesenfeld considered process of successive random placement of sand grains on the grid; each such placement of sand at a particular site may have no effect, or it may cause a cascading reaction that will affect many sites.

The model has since been studied on the infinite lattice, on other (non-square) lattices, and on arbitrary graphs (including directed multigraphs). It is closely related to the dollar game, a variant of the chip-firing game introduced by Biggs.