A signed integer is a type of whole number that can represent both positive and negative values. In computer programming and mathematics, signed integers are typically used to perform calculations that require the ability to express values below zero, such as temperature or financial data. They are usually stored in a fixed number of bits, with one bit designated for the sign (positive or negative). For example, in a 32-bit signed integer, the range of values can go from -2,147,483,648 to 2,147,483,647. This allows for a wide variety of applications, including data analysis and game development, where both positive and negative numbers are essential for accurate representation and computation.