A relational operator is a symbol used in programming and mathematics to compare two values or expressions. Common relational operators include greater than (>) and less than (<), which help determine the relationship between numbers. These operators return a boolean value, either true or false, based on the comparison. In programming languages like Python or Java, relational operators are essential for controlling the flow of a program. They are often used in conditional statements, such as if statements, to execute specific code based on whether a condition is met. This allows for dynamic decision-making in software applications.