## Definition, Concept, Meaning, What is Variable

### 1. Concept of Variable

A variable is the symbolic expression of an unspecified element in a set. This set consisting of all elements or variables, that can replace each other is the universe of variables. They are so called because they vary, and this variation is observable and measurable.
Variables can be quantitative, when expressed in numbers, such as the length or weight. Qualitative variables expressed qualities, for example, designate letters preferences of students by their fields of study.
Continuous variables are which can have any value as a weight or height. The staple have particular values, as for example, the number of children in a family.
The dependent variables, which are the subject of research, for example, growth and development of children, are which are modified by the independent, for example certain foodstuff. What we want to see is if that food stimulates the growth of children. The variable to study is the dependent, as it is those who observe, and will alter the consumption of the independent variable. There are also strange variables that can influence like that also the children practice sports. In this case it should be delete them, for example suppressing the practice of sports in the period of study to avoid contamination research, since for example we don't know if they grew for the sport or for the foodstuff.
In computer science the term variable is used to designate, in the programming language, a data type, which has been assigned a value, which may vary during the execution of the program.

### 2 Meaning of Variable

A Variable is an object with some identity, but the environment that surrounds it obliges it to vary on the circumstances that arise. One of the applications that is more given to the term is in mathematics, since when we are presented with an equation, it is in order to give a fixed and exact value to one or more variables, this condition, make troubleshooting simpler. Equations are the easiest to operate mathematically complex situations, in which exact quantities to precise values must be determined. Variables are usually responses are given to problems.
From a social point of view, the term variable corresponds in some way such as in mathematics, without numbers is clear, but variables include each of the situations, circumstances, options and ways to solve a problem. The term comes from the latin "Variabilis, it refers to"Variety", with this we do focus on the idea that the variables are not more than alternatives to take a path, course, from here the concept is purely abstract, since it has the ability to adapt to any situation by very versada to be." In the universe of things, which includes the explanation of every situation in life, it could be argued that each variable has a response, however, this will always be an assertion without a base clear.
The variables are diversified according to the use that is given, for example, if the nominal value for a variable is not necessary the search for its value through any function or expression showing me how to do it. The variables that express a relationship with some features qualify the conditions of something that is always that way, if altered their behavior or functions, turn another quality. Computer science, astronomy, chemistry, physics in any of their denominations, use the term to refer to changes in the study being carried out.

### 3. Definition and what is Variable

Derived from the term in latin variabilis, variable is a word that represents what that varies or is subject to some kind of change. It is characterized for being unstable, changeable and inconstant. In other words, a variable is a symbol that identifies an item not specified within a particular group. This group tends to be defined as a universal set of the variable (the variable, sometimes universe), and each piece added is a value of the variable.
For example: x is a variable of the universe {1, 3, 5, 7}. Therefore, x may be equal to any of the newly listed securities, with which it is possible to replace x with any odd number that is less than 8.
As you can notice, the variables are elements in formulas, selection and algorithms, which can be replaced or can purchase without belonging to a same universe, different values. It is worth mentioning that the values of a variable can be framed within a range or be limited by conditions of membership.
You can talk about different types of variable: dependent variables, which are those that depend on the value assigned to other phenomena or variables; the independent variables, whose value changes influence the values of another; the random variables are the functions associated with a real number to each element of a set E.
In another classification, you can say that there are qualitative variables, which express different qualities, characteristics, or modalities, and quantitative variables, which are set out through numerical quantities, among others. Within the qualitative variables are the nominal (those that are not numerical and either can be ordered, as for example the civil status) and the ordinals or cuasicuantitativa (are non-numeric but yes can be ordered, as the note of the tests). For its part, the quantitative variables can be discrete (not allowed intermediate values but exact numbers, for example the number of siblings of a person) or continuous (those that accept intermediate values between two numbers, e.g. measures of weight and height).
In the field of programming (computer science), the variables are data structures that can change their content throughout the execution of a program. These structures correspond to a quiet area in the main memory of the computer.
Each variable the programmer assigned a tag that allows you to recognize it from the rest, in this way whenever you need it you can call that variable and will come with the value that has been assigned to you. For example, if the variable name "num" and is stored with the number 7. If the programmer wishes to use it could program: num = num + 1 and get a result that precedes the variable.
In programming variables are classified in another way, there are type Boolean, decimal floating point, arrangement, matrix and random, among others.
Variables are the basis of programming, respond to a language and allow the programmer can perform the work of orderly and efficient. The sum of the variables are those that give as a result a certain action in a program and they always respond to the wishes of the programmer. This means that you out of an engine or the code of a given program these variables can mean something else and therefore their sum be different, because every programmer can assign the values that you want to to each of the variables in your code.
Finally, it is worth mentioning that, in astronomy, the variable stars are those who experience significant variations in luminosity.