An "expert" (reliable source of technique or skill whose faculty for judging or deciding rightly, justly, or wisely is accorded authority and status by their peers or the public. Reliabilism a category of theories in the philosophical discipline of Epistemology, has been advanced both as a theory of Knowledge and of justified A skill is the learned capacity or talent to carry out pre-determined results often with the minimum outlay of time energy or both. A peer group is a group of approximately the same age Social status, and interests An expert, more generally, is a person with extensive knowledge or ability in a particular area of study. Knowledge is defined ( Oxford English Dictionary) variously as (i expertise and skills acquired by a person through experience or education the theoretical or practical understanding An aptitude is an innate acquired or learned or developed component of a competency ( being the others knowledge understanding and attitude) to do a certain kind of work Experts are called in for advice on their respective subject, but they do not always agree on the particulars of a field of study. An expert can be, by virtue of training, education, profession, publication or experience, believed to have special knowledge of a subject beyond that of the average person, sufficient that others may officially (and legally) rely upon the individual's opinion. The term training refers to the acquisition of knowledge skills and competencies as a result of the teaching of vocational or practical skills and knowledge Education encompasses both the Teaching and Learning of Knowledge, proper conduct, and technical competency The term profession is applied to those persons who have specialized and technical skill or knowledge which they apply for a fee to certain tasks that ordinary and unqualified people cannot To publish is to make content Publicly known. The term is most frequently applied to the distribution of text or images on paper or to the placing of content Experience as a general concept comprises Knowledge of or skill in or Observation of some thing or some event gained through involvement in or An official is someone who holds an office (function or mandate, regardless whether it carries an actual working space with it in an Organisation or Law is a system of rules enforced through a set of Institutions used as an instrument to underpin civil obedience politics economics and society An opinion is a Person 's Ideas and thoughts towards something which it is either impossible to verify the truth of or the truth of which is thought unimportant to Historically, an expert was referred to as a sage. The individual was usually a profound philosopher distinguished for wisdom and sound judgment. Philosophy is the study of general problems concerning matters such as existence knowledge truth beauty justice validity mind and language Wisdom is a concept of personal gaining of Knowledge, Understanding, Experience, discretion and intuitive understanding, along with a capacity In non-legal contexts a judgment is a balanced weighing up of evidence preparatory to making a decision) is someone widely recognized as a
Experts have a prolonged or intense experience through practice and education in a particular field. In specific fields, the definition of expert is well established by consensus and therefore it is not necessary for an individual to have a professional or academic qualification for them to be accepted as an expert. In this respect, a shepherd with 50 years of experience tending flocks would be widely recognized as having complete expertise in the use and training of sheep dogs and the care of sheep. Another example from computer science is that an expert system may be taught by a human and thereafter considered an expert, often outperforming human beings at particular tasks. Computer science (or computing science) is the study and the Science of the theoretical foundations of Information and Computation and their An expert system is Software that attempts to reproduce the performance of one or more human Experts most commonly in a specific Problem domain, and is In law, an expert witness must be recognized by argument and authority. Law is a system of rules enforced through a set of Institutions used as an instrument to underpin civil obedience politics economics and society An expert witness is a Witness, who by virtue of Education, Training, Skill, or Experience, is believed to have Knowledge In Logic, an argument is a Set of one or more Declarative sentences (or "propositions") known as the Premises along In Politics, authority ( Latin Auctoritas, used in Roman law as opposed to Potestas and Imperium
Expertise consists of those characteristics, skills and knowledge of a person (that is, expert) or of a system, which distinguish experts from novices and less experienced people. In many domains there are objective measures of performance capable of distinguishing experts from novices: expert chess players will almost always win games against recreational chess players; expert medical specialists are more likely to diagnose a disease correctly; etc. A specialty in Medicine is a branch of medical science other than General practice.
There are broadly two academic approaches to the understanding and study of expertise. The first understands expertise as an emergent property of communities of practice. "CoP" redirects here This article is about "Communities of Practice" In this view expertise is socially constructed; tools for thinking and scripts for action are jointly constructed within social groups enabling that group jointly to define and acquire expertise in some domain.
In the second view expertise is a characteristic of individuals and is a consequence of the human capacity for extensive adaptation to physical and social environments. Many accounts of the development of expertise emphasise that it comes about though long periods of deliberate practice. In many domains of expertise estimates of 10 years experience or 10,000 hours deliberate practice are common. Typically recent research on expertise emphasises the nurture side of the nature versus nurture argument. The nature versus nurture debates concern the relative importance of an individual's innate qualities ("nature" i  It should be noted that some factors not fitting the nature versus nurture dichotomy are important as well. These typically are biological but not genetic factors, and include starting age, handedness, and season of birth.  
A number of computational models have been developed in cognitive science to explain the development from novice to expert. Cognitive science may be broadly defined as the multidisciplinary study of mind and behavior In particular, Herbert Simon and Kevin Gilmartin proposed a model of learning in chess called MAPP (Memory-Aided Pattern Recognizer). Herbert Alexander Simon ( June 15, 1916 February 9, 2001) was an American Political scientist whose research ranged  Based on simulations, they estimated that about 50,000 chunks (units of memory) are necessary to become an expert, and hence the many years needed to reach this level. In Cognitive psychology and Mnemonics, chunking refers to a strategy for making more efficient use of short-term memory by recoding information More recently, the CHREST model (Chunk Hierarchy and REtrieval STructures) has simulated in detail a number of phenomena in chess expertise (eye movements, performance in a variety of memory tasks, development from novice to expert) and in other domains. CHREST (Chunk Hierarchy and REtrieval STructures is a symbolic Cognitive architecture based on the concepts of limited attention limited short-term memories and Chunking  
Work on expert systems typically works from the premise that expertise is based on acquired repertoires of rules and frameworks for decision making which can be elicited as the basis for computer supported judgement and decision-making. An expert system is Software that attempts to reproduce the performance of one or more human Experts most commonly in a specific Problem domain, and is However, there is increasing evidence that expertise does not work in this fashion. Rather, experts recognise situations based on experience of many prior situations. They are in consequence able to make rapid decisions in complex and dynamic situtions relying on recognition-primed decision-making.
In a critique of the expert systems literature, Dreyfus and Dreyfus  suggest:
If one asks an expert for the rules he or she is using, one will, in effect, force the expert to regress to the level of a beginner and state the rules learned in school. Thus, instead of using rules he or she no longer remembers, as the knowledge engineers suppose, the expert is forced to remember rules he or she no longer uses. … No amount of rules and facts can capture the knowledge an expert has when he or she has stored experience of the actual outcomes of tens of thousands of situations. ”
An important feature of expert performance seems to be the way in which experts are able to rapidly retrieve complex configurations of information from long-term memory. They recognise situations because they have meaning. It is perhaps this central concern with meaning and how it attaches to situations which provides an important link between the individual and social approaches to the development of expertise.
In line with the socially constructed view of expertise, expertise can also be understood a form of power; that is, experts have the ability to influence others as a result of their defined social status. Power is a measure of a person's ability to control the environment around them including the behavior of other people
Plato’s ‘Noble Lie’, albeit arguably a notion of ideological propaganda, is often where the debate begins concerning ‘expertise’. Plato did not believe most people were clever enough to look after their own and society’s best interest, so the few ‘clever’ people of the world needed to lead the rest of the flock. Therefore, the idea was born that only the elite should know the truth in its complete form and the rulers, Plato said, must tell the people of the city ‘The Noble Lie’ to keep them passive and content, without the risk of upheaval and unrest. Thus, the creation of an elite form of specialist and authoritative knowledge came about.
In contemporary society, doctors and scientists, for example, are considered to be experts in that they hold a body of dominant knowledge that is, on the whole, inaccessible to the layman (Fuller: 2005: 141). However, this inaccessibility and perhaps even mystery that surrounds expertise does not cause the layman to disregard the opinion of the experts on account of the unknown. Instead, the complete opposite occurs whereby members of the public believe in and highly value the opinion of medical professionals or of scientific discoveries (Fuller: 2005: 144), despite not understanding it.
Marie-Line Germain (Germain, 2006) developed a measure of perception of employee expertise called the Generalized Expertise Measure (GEM). She also found that there is a behavioral dimension found in "experts", in addition to the dimensions suggested by Swanson and Holton (2001). The 16-item scale contains objective expertise items and subjective expertise items. Objective items (the first 5 items of the measure below) were named Evidence-Based items. Subjective items (the remaining 11 items from the measure below) were named Self-Enhancement items because of their behavioral component.
With a sample of N=307, the scale reliability (internal consistency, Cronbach Alpha coefficient) of the 16-item scale was high (. 91 for the five Evidence-Based items and . 92 for the eleven Self-Enhancement items).
An expert differs from the specialist in that a specialist has to be able to solve a problem and an expert has to know its solution. A problem is an obstacle which makes it difficult to achieve a desired goal objective or purpose The opposite of an expert is generally known as a layperson, while someone who occupies a middle grade of understanding is generally known as a technician and often employed to assist experts. The term " layman " originated from the use of the term Laity, but over the centuries changed definition to mean a person who is a non-expert in a given field of A technician is generally someone in a technological field who has a relatively practical understanding of the general theoretical principles of that field e A person may well be an expert in one field and a layperson in many other fields. The concepts of experts and expertise are debated within the field of epistemology under the general heading of expert knowledge. Epistemology (from Greek επιστήμη - episteme, "knowledge" + λόγος, " Logos " or theory of knowledge In contrast, the opposite of a specialist would be a generalist, somebody with expertise in many fields.
The term is widely used informally, with people being described as 'experts' in order to bolster the relative value of their opinion, when no objective criteria for their expertise is available. "n objective account is one which attempts to capture the nature of the object studied in a way that does not depend on any features of the particular subject who studies it The term crank is likewise used to disparage opinions. "Crank" is a Pejorative term for a person who either holds some belief which the vast majority of his contemporaries would consider false is eccentric (especially Academic elitism arises when experts become convinced that only their opinion is useful, sometimes on matters beyond their personal expertise. Academic elitism is a charge sometimes levied at Academic institutions and academics more broadly use of the term " Ivory tower " often carries with it
By a similar token, a fear of experts can arise from fear of an intellectual elite's power. In earlier periods of history, simply being able to read made one part of an intellectual elite. The introduction of the printing press in Europe during the fifteenth century and the diffusion of printed matter contributed to higher literacy rates and wider access to the once-rarefied knowledge of academia. A printing press is a mechanical device for applying pressure to an inked surface resting upon a medium (such as paper or cloth thereby transferring an image The subsequent spread of education and learning changed society, and initiated an era of widespread education whose elite would now instead be those who produced the written content itself for consumption, in education and all other spheres.
In contrast to an expert, a novice (known colloquially as a newbie or 'greenhorn') is any person that is new to any science or field of study or activity or social cause and who is undergoing training in order to meet normal requirements of being regarded a mature and equal participant. For the city in Texas, see Novice Texas. Buddhism See also Buddhist Novitiate In many Buddhist A colloquialism is an expression not used in formal speech, writing or Paralinguistics. Newbie (also said as nooby or newby is a slang term for a newcomer to Online gaming or an Internet activity
Some characteristics of the development of an expert have been found to include
Mark Twain defined an expert as "an ordinary fellow from another town". Samuel Langhorne Clemens (November 30 1835 – April 21 1910 better known by the Pen name Mark Twain, was an American Humorist, satirist  Will Rogers described an expert as "A man fifty miles from home with a briefcase. This page is about the humorist for others with similar names see William Rogers. "