A conditional expression is a programming construct that evaluates a condition and returns a value based on whether the condition is true or false. It is often used to simplify code by allowing a single line to determine which value to use. For example, in languages like Python or JavaScript, a conditional expression can be written using the syntax `condition ? value_if_true : value_if_false`. These expressions are particularly useful in situations where you want to assign a value or execute a function based on a specific condition without using multiple lines of code. They enhance code readability and efficiency, making it easier to manage logic in programs.