Conditional expressions are a programming construct that evaluates a condition and returns a value based on whether the condition is true or false. They are often used to simplify code by allowing a single line to determine outcomes instead of using multiple lines with if-else statements. For example, in languages like Python or JavaScript, a conditional expression can be written using the syntax `x if condition else y`, where `x` is returned if the condition is true, and `y` is returned if it is false. These expressions enhance code readability and efficiency, making it easier for developers to implement logic in their programs. They are particularly useful in scenarios where a quick decision is needed, such as assigning values or filtering data. By using conditional expressions, programmers can write cleaner and more concise code, which is easier to maintain and understand.