Parameter vs. Variable — What's the Difference?

A variable in a function definition used to accept input.

A named location that stores data values.

Acts as a placeholder for data passed to functions.

Integral to both simple and complex programming tasks.

Determines the function's input interface.

Can be reassigned and manipulated.

Defined within the parentheses of a function definition.

Can have different data types.

Specific to the function's scope.

Used throughout programming for data storage.

A parameter (from the Ancient Greek παρά, para: "beside", "subsidiary"; and μέτρον, metron: "measure"), generally, is any characteristic that can help in defining or classifying a particular system (meaning an event, project, object, situation, etc.). That is, a parameter is an element of a system that is useful, or critical, when identifying the system, or when evaluating its performance, status, condition, etc.

Likely to change or vary; subject to variation; changeable.

A numerical or other measurable factor forming one of a set that defines a system or sets the conditions of its operation

Inconstant; fickle.

A limit or boundary which defines the scope of a particular process or activity

(Biology) Tending to exhibit genetic variation or variation in a physical trait

A constant in an equation that varies in other equations of the same general form, especially such a constant in the equation of a curve or surface that can be varied to represent a family of curves or surfaces.

(Mathematics) Having no fixed quantitative value.

One of a set of independent variables that express the coordinates of a point.

Something that varies or is prone to variation.

One of a set of measurable factors, such as temperature and pressure, that define a system and determine its behavior and are varied in an experiment.

(Astronomy) A variable star.

Usage Problem A factor that restricts what is possible or what results

A quantity capable of assuming any of a set of values.

A factor that determines a range of variations; a boundary

A symbol representing such a quantity. For example, in the expression a2 + b2 = c2, a,b, and c are variables.

(Statistics) A quantity, such as a mean, that is calculated from data and describes a population.

Able to vary or be varied.

Usage Problem A distinguishing characteristic or feature.

Likely to vary.

A value kept constant during an experiment, equation, calculation, or similar, but varied over other versions of the experiment, equation, calculation, etc.

Marked by diversity or difference.

(sciences) A variable that describes some system (material, object, event, etc.) or some aspect thereof.

(mathematics) Having no fixed quantitative value.

(statistics) Any measured quantity of a statistical population that summarises or describes an aspect of the population.

(biology) Tending to deviate from a normal or recognized type.

(machine learning) A variable of a model that is trained by a machine learning algorithm.

Something that is variable.

(programming) An input variable of a function definition, that gets an actual value (argument) at execution time.

Something whose value may be dictated or discovered.

An actual value given to such a formal parameter.

(mathematics) A symbol representing a variable.

A characteristic or feature that distinguishes something from others.

(programming) A named memory location in which a program can store intermediate results and from which it can read them.

(geometry) In the ellipse and hyperbola, a third proportional to any diameter and its conjugate, or in the parabola, to any abscissa and the corresponding ordinate.

(astronomy) A variable star.

(crystallography) The ratio of the three crystallographic axes which determines the position of any plane.

(nautical) A shifting wind, or one that varies in force.

(crystallography) The fundamental axial ratio for a given species.

Those parts of the sea where a steady wind is not expected, especially the parts between the trade-wind belts.

A constant number which is part of a theory, function, or calculation, whose value is not determined by the form of the theory or equation itself, and may in some cases be arbitrary assigned.

Having the capacity of varying or changing; capable of alternation in any manner; changeable; as, variable winds or seasons; a variable quantity.

A term applied to some characteristic magnitude whose value, invariable as long as one and the same function, curve, surface, etc., is considered, serves to distinguish that function, curve, surface, etc., from others of the same kind or family.

Liable to vary; too susceptible of change; mutable; fickle; unsteady; inconstant; as, the affections of men are variable; passions are variable.

Any constant number which is required to calculate values of observed phenomena according to a theory, but the value of which must be determined by experiment, and cannot be calculated from the fundamental assumptions of the theory. In general, a theory which has a large number of parameters, though it may accurately predict experimental results, is considered as having less explanatory power and as being less esthetically pleasing than a theory with fewer parameters.

That which is variable; that which varies, or is subject to change.

The ratio of the three crystallographic axes which determines the position of any plane; also, the fundamental axial ratio for a given species.

A quantity which may increase or decrease; a quantity which admits of an infinite number of values in the same expression; a variable quantity; as, in the equation x2 - y2 = R2, x and y are variables.

The limits, guidelines, or assumptions from within which an activity is carried out; as, new arrivals need to learn the parameters of the research in our department.

A shifting wind, or one that varies in force.

A variable used in a calculation within a computer program which must be assigned a value before the calculation can be performed; as, let's plug in the parameters and see what the result is.

Something that is likely to vary; something that is subject to variation;

A characteristic or element, especially one used as a criterion for evaluation or judgment; as, a useful parameter for determining efficiency.

A quantity that can assume any of a set of values

A constant in the equation of a curve that can be varied to yield a family of similar curves

A star that varies noticeably in brightness

Any factor that defines a system and determines (or limits) its performance

A symbol (like x or y) that is used in mathematical or logical expressions to represent a variable quantity

A quantity (such as the mean or variance) that characterizes a statistical population and that can be estimated by calculations from sample data

Liable to or capable of change;

Marked by diversity or difference;

(used of a device) designed so that a property (as e.g. light) can be varied;

Parameters have a local scope within the function they belong to, while variables can have local or global scopes depending on where they are declared.

Yes, but within a function, the parameter name will take precedence within the function's scope.

Yes, variables can be passed as arguments to functions, where they correspond to the function's parameters.

A parameter is a named entity in a function definition, serving as a placeholder for data that the function can accept as input.

Variables are essential for storing, retrieving, and manipulating data, making them fundamental to program operation.

Parameters are reinitialized with each function call, while variables can be reused and reassigned multiple times.

Parameters allow functions to accept different inputs, making them versatile and reusable for various data.

By allowing functions to operate on different sets of data without needing to change the function's code.

No, parameters are specific to functions and exist only within the context of function definitions and calls.

A variable is a named storage location in a program that can hold a value, which may change during program execution.

Yes, functions can have multiple parameters, separated by commas in the function definition.

In some programming languages, variables must be initialized upon declaration, while in others, they can be declared without initialization.

Yes, in many programming languages, parameters can have default values, used if no argument is passed.

No, some functions may not require any parameters and operate without them.

Variables are used in loops, conditionals, and global settings, among other programming constructs, to store and manipulate data.