What keyword is commonly used to declare a variable in many programming languages?

To declare a variable in programming, the use of 'Dim' is prominently associated with languages like Visual Basic. It stands for "Dimension" and is used to specify the data type and allocate storage space for the variable. By declaring a variable using this keyword, the programmer makes it clear that a new variable is being introduced and defines its type, which can enhance code readability and maintainability.

While 'Var' is also commonly used in many modern programming languages (such as JavaScript and Swift) to declare variables, each language may have specific context or rules about how these keywords are used. For example, 'Set' is often associated with assigning a value to an object in Visual Basic rather than declaring a variable itself. Similarly, 'Declare' is not typically used as a keyword for variable declaration across the majority of languages.

Thus, 'Dim' is the keyword that signifies the process of declaring a new variable, particularly in environments where it defines the variable's scope and data type.