Science

In biology, taxonomy (from Ancient Greek τάξις (taxis) 'arrangement' and -νομία (-nomia) 'method') is the scientific study of naming, defining (circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon), and these groups are given a taxonomic rank; groups of a given rank can be aggregated to form a more inclusive group of higher rank, thus creating a taxonomic hierarchy. The principal ranks in modern use are domain, kingdom, phylum (division is sometimes used in botany in place of phylum), class, order, family, genus, and species. The Swedish botanist Carl Linnaeus is regarded as the founder of the current system of taxonomy, having developed a ranked system known as Linnaean taxonomy for categorizing organisms.

With advances in the theory, data and analytical technology of biological systematics, the Linnaean system has transformed into a system of modern biological classification intended to reflect the evolutionary relationships among organisms, both living and extinct.

The International System of Units, internationally known by the abbreviation SI (from French Système international d'unités), is the modern form of the metric system and the world's most widely used system of measurement. It is the only system of measurement with official status in nearly every country in the world, employed in science, technology, industry, and everyday commerce. The SI system is coordinated by the International Bureau of Weights and Measures, which is abbreviated BIPM from French: Bureau international des poids et mesures.

The SI comprises a coherent system of units of measurement starting with seven base units, which are the second (symbol s, the unit of time), metre (m, length), kilogram (kg, mass), ampere (A, electric current), kelvin (K, thermodynamic temperature), mole (mol, amount of substance), and candela (cd, luminous intensity). The system can accommodate coherent units for an unlimited number of additional quantities. These are called coherent derived units, which can always be represented as products of powers of the base units. Twenty-two coherent derived units have been provided with special names and symbols.

Acatalepsy (from the Greek α̉- 'privative' and καταλαμβάνειν 'to seize'), in philosophy, is incomprehensibleness, or the impossibility of comprehending or conceiving some or all things. The doctrine held by the ancient Skeptic philosophers, that human knowledge never amounts to certainty, but only to probability.

The Pyrrhonians attempted to show, while Academic skeptics of the Platonic Academy asserted an absolute acatalepsia; all human science or knowledge, according to them, went no further than to appearances and verisimilitude. It is the antithesis of the Stoic doctrine of katalepsis or Apprehension. According to the Stoics, katalepsis was true perception, but to the Skeptics, all perceptions were acataleptic, i.e. bear no conformity to the objects perceived, or, if they did bear any conformity, it could never be known.

The reputation or prestige of a social entity (a person, a social group, an organization, or a place) is an opinion about that entity – typically developed as a result of social evaluation on a set of criteria, such as behavior or performance.

Reputation is a ubiquitous, spontaneous, and highly efficient mechanism of social control. It is a subject of study in social, management, and technological sciences. Its influence ranges from competitive settings, like markets, to cooperative ones, like firms, organizations, institutions and communities. Furthermore, reputation acts on different levels of agency: individual and supra-individual. At the supra-individual level, it concerns groups, communities, collectives and abstract social entities (such as firms, corporations, organizations, countries, cultures and even civilizations). It affects phenomena of different scales, from everyday life to relationships between nations. Reputation is a fundamental instrument of social order, based upon distributed, spontaneous social control.

Chronology (from Latin chronologia, from Ancient Greek χρόνος, chrónos, 'time'; and -λογία, -logia) is the science of arranging events in their order of occurrence in time, such as in a timeline or other sequence of events. It is also "the determination of the actual temporal sequence of past events".

Chronology is a part of periodization. It is also a part of the discipline of history including earth history, the earth sciences, and study of the geologic time scale.

Alexandria is a major city in Egypt. Lying at the western edge of the Nile River Delta, it extends about 40 km (25 mi) along the country's northern coast. It is Egypt's principal seaport, the second largest city after Cairo, and the largest city on the Mediterranean coast. Founded in 331 BC by Alexander the Great, Alexandria is one of the largest and most important cities of antiquity and a leading hub for science, culture, and scholarship.

Nicknamed the "Bride of the Mediterranean" and "Pearl of the Mediterranean Coast", the city is a popular tourist destination and a major industrial centre. It is the sixth-largest city in the Arab world and in the Middle East, and the eleventh-largest city and urban area in Africa. Alexandria was established originally near an ancient Egyptian settlement named Rhacotis, which later became its Egyptian quarter. The city was made the capital of the Ptolemaic Kingdom and became the foremost commercial, intellectual, and cultural centre for much of the Hellenistic age and late antiquity; at one time, it was the most populous city in the ancient world. Alexandria was best known for the Lighthouse of Alexandria (Pharos), one of the Seven Wonders of the Ancient World; its Great Library, the largest in the ancient world; and the Catacombs of Kom El Shoqafa, one of the Seven Wonders of the Middle Ages.

Humans, scientifically known as Homo sapiens, are primates that belong to the biological family of great apes and are characterized by hairlessness, bipedality, and high intelligence. Humans have large brains compared to body size, enabling more advanced cognitive skills that facilitate successful adaptation to varied environments, development of sophisticated tools, and formation of complex social structures and civilizations.

Humans are highly social, with individual humans tending to belong to a multi-layered network of distinct social groups – from families and peer groups to corporations and political states. As such, social interactions between humans have established a wide variety of values, social norms, languages, and traditions (collectively termed institutions), each of which bolsters human society. Humans are also highly curious: the desire to understand and influence phenomena has motivated humanity's development of science, technology, philosophy, mythology, religion, and other frameworks of knowledge; humans also study themselves through such domains as anthropology, social science, history, psychology, and medicine. As of 2025, there are estimated to be more than 8 billion living humans.

Probability is a branch of mathematics and statistics concerning events and numerical descriptions of how likely they are to occur. The probability of an event is a number between 0 and 1; the larger the probability, the more likely an event is to occur. This number is often expressed as a percentage (%), ranging from 0% to 100%. A simple example is the tossing of a fair (unbiased) coin. Since the coin is fair, the two outcomes ("heads" and "tails") are both equally probable; the probability of "heads" equals the probability of "tails"; and since no other outcomes are possible, the probability of either "heads" or "tails" is 1/2 (which could also be written as 0.5 or 50%).

These concepts have been given an axiomatic mathematical formalization in probability theory, which is used widely in areas of study such as statistics, mathematics, science, finance, gambling, artificial intelligence, machine learning, computer science, game theory, and philosophy to, for example, draw inferences about the expected frequency of events. Probability theory is also used to describe the underlying mechanics and regularities of complex systems.

A laboratory (UK: /ləˈbɒrətəri/; US: /ˈlæbrətɔːri/; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratories are found in a variety of settings such as schools, universities, privately owned research institutions, corporate research and testing facilities, government regulatory and forensic investigation centers, physicians' offices, clinics, hospitals, regional and national referral centers, and even occasionally personal residences.

Technology is the application of conceptual knowledge to achieve practical goals, especially in a reproducible way. The word technology can also mean the products resulting from such efforts, including both tangible tools such as utensils or machines, and intangible ones such as software. Technology plays a critical role in science, engineering, and everyday life.

Technological advancements have led to significant changes in society. The earliest known technology is the stone tool, used during prehistory, followed by the control of fire—which in turn contributed to the growth of the human brain and the development of language during the Ice Age, according to the cooking hypothesis. The invention of the wheel in the Bronze Age allowed greater travel and the creation of more complex machines. More recent technological inventions, including the printing press, telephone, and the Internet, have lowered barriers to communication and ushered in the knowledge economy.