A "variablename" is a placeholder used in programming and mathematics to represent a value that can change. It allows developers and mathematicians to write formulas and code that can adapt to different inputs. For example, in the equation y = mx + b, x and y are variable names that can take on different values. In programming, variable names are essential for storing data. They can hold various types of information, such as numbers, text, or objects. Good variable names are descriptive, making it easier for others to understand the code. For instance, a variable named totalScore clearly indicates it holds a score value.