Interaction

Interaction is a kind of action that occurs as two or more objects have an effect upon one another. The idea of a two-way effect is essential in the concept of interaction, as opposed to a one-way causal effect. Closely related terms are interactivity and interconnectivity, of which the latter deals with the interactions of interactions within systems: combinations of many simple interactions can lead to surprising emergent phenomena. "Interaction" has different tailored meanings in various sciences. Changes can also involve interaction.
Casual examples of interaction outside science include:
Physics.
In physics, a fundamental interaction (depending on the nature of the interaction, it might also be called a fundamental force) is a process by which elementary particles interact with each other. An interaction is often described as a physical field, and is mediated by the exchange of gauge bosons between particles. For example, the interaction of charged particles takes place through the mediation of electromagnetic fields, whereas beta decay occurs by means of the weak interaction. An interaction is fundamental when it cannot be described in terms of other interactions. There are four known fundamental interactions in nature: The electromagnetic, strong, weak and gravitational interactions. The weak and electromagnetic interactions are unified in electroweak theory, which has been theoretically unified with the strong force in the standard model, but experimental results are yet to prove this.
Chemistry.
Interactions between atoms and molecules:
Biochemistry.
Molecular biology.
In molecular biology, the knowledge on gene/protein interaction among themselves and with their metabolites is referred to as molecular pathways.
Medicine and pharmacology.
In medicine, most medications can be safely used with other medicines, but particular combinations of medicines need to be monitored for interactions, often by the pharmacist. Interactions between medications fall generally into one of two main categories:
In terms of efficacy, there can be three types of interactions between medications: additive, synergistic, and antagonistic.
Biology and genetics.
Geneticists work with a number of different genetic interaction modes to characterize how the combination of two mutations affect (or does not affect) the phenotype:
noninteractive, synthetic, asynthetic, suppressive, epistatic, conditional, additive, single-nonmonotonic and double-nonmonotonic.
Further characterizations is enhancement interaction and nonadditive interaction. Biosemioticists investigate sign-mediated interactions within and between organisms that underlie syntactic, pragmatic and semantic rules.
The word epistasis is also used for genetic interaction in some contexts.
Sociology.
In sociology, social interaction is a dynamic, changing sequence of social actions between individuals (or groups) who modify their actions and reactions due to the actions by their interaction partner(s). Social interactions can be differentiated into accidental, repeated, regular, and regulated. Social interactions form the basis of social relations.
The most common forms of social interaction are exchange, competition, conflict, cooperation, and accommodation.
Statistics.
In statistics, an interaction is a term in a statistical model in which the effect of two, or more, variables is not simply additive.
An example from statistics applied to health science.
If we were examining the effect of two variables, gender and premature birth, on health outcomes, we would describe any difference in health outcome scores between genders as a main effect. Similarly any difference in scores of full term/premature birth would be described as a main effect. The presence of an interaction effect implies that the effect of gender on health outcome varies as a function of premature birth status.
Media art.
In media, interactivity is a feature of the media in question and as digital technology becomes more accessible to the masses interest in interactivity is increasing and becoming a cultural trend especially in the arts.