A ghostwriter is a writer who writes books, articles, stories, reports or other texts that are officially credited to another person.

Sabotage is when a student prevents others from completing their work. This includes cutting pages out of library books, deleting data from classmate's computer or otherwise willfully disrupting the experiments of others.

Cross tabulation (or crosstabs for short) is a statistical process that summarizes categorical data to create a contingency table. They are heavily used in survey research, business intelligence, engineering and scientific research. They provide a basic picture of the interrelation between two variables and can help find interactions between them.

Chemically, about three quarters of the Sun's mass consists of hydrogen, while the rest is mostly helium.

The term epistemic feedback is a form of feedback which refers to an interplay between what is being observed (or measured) and the result of the observation. The concept can apply to a process to obtain information, where the process, itself, changes the information when being obtained. For example, instead of quietly asking customers for their opinions about food in a restaurant, making an announcement about food quality, as being tested in a survey, could cause cooks to focus on having high-quality results.

When a probability density function has multiple local maxima, it is common to refer to all of the local maxima as modes of the distribution. Such a continuous distribution is called multimodal (as opposed to unimodal).

Uncertainty reduction theory comes from the sociopsychological perspective. It addresses the basic process of how we gain knowledge about other people. According to the theory, people have difficulty with uncertainty, they want to be able to predict behavior and therefore they are motivated to seek more information about people.

Conservation is an ethic of resource use, allocation, and protection. Its primary focus is upon maintaining the health of the natural world, its fisheries, habitats and biological diversity.

Indian nationality law largely follows the jus sanguinis (citizenship by right of blood) as opposed to the jus soli (citizenship by right of birth within the territory).

Soil acidification is the buildup of hydrogen cations, also called protons, reducing the soil pH. This happens when a proton donor gets added to the soil. The donor can be an acid, such as nitric acid and sulfuric acid (these acids are common components of acid rain).

Formative assessment or diagnostic testing is a range of formal and informal assessment procedures employed by teachers during the learning process in order to modify teaching and learning activities to improve student attainment. It typically involves qualitative feedback (rather than scores) for both student and teacher that focuses on the details of content and performance.

An intelligent tutoring system (ITS) is a computer system that aims to provide immediate and customized instructions or feedback to learners, usually without intervention from a human teacher.

Ecological collapse refers to a situation where an ecosystem suffers a drastic, possibly permanent, reduction in carrying capacity for all organisms, often resulting in mass extinction. Usually, an ecological collapse is precipitated by a disastrous event occurring on a short time scale.

Web servers are computers that deliver (serves up) web pages. Every web server has an IP address and possibly a domain name.

A digital signature is a mathematical scheme for demonstrating the authenticity of a digital message or document. A valid digital signature gives a recipient, reason to believe that the message was created by a known sender, such that the sender cannot deny having sent the message (authentication and non-repudiation) and that the message was not altered in transit (integrity). Digital signatures are commonly used for software distribution, financial transactions and in other cases where it is important to detect forgery or tampering.