A boolean is a data type that can hold exactly two values, typically written as true or false. Booleans are the foundation of conditional logic and control flow in most programming languages. They are used to represent yes or no answers, on or off states, and the results of comparisons. For example, checking whether a variable is greater than zero produces a boolean value. Booleans are cheap to store and compute, which makes them efficient for repeated checks inside loops. Even though the concept is simple, many bugs come from misunderstanding how boolean expressions are combined. Booleans are also important in configuration flags, feature toggles, and security checks.
Key Characteristics
Boolean expressions are built using logical operators such as AND, OR, and NOT, which combine or invert boolean values. In many languages, non boolean values like numbers or strings can be converted to booleans using truthiness rules, which can surprise developers if they are not careful. Conditionals like if statements or while loops evaluate a boolean expression to decide which branch to execute or whether to continue. When designing APIs or JSON payloads, booleans are useful for clear flags such as is_admin or is_active. Good naming matters; a boolean field should read naturally when you plug true or false into the sentence. With AI assistance, it is helpful to state boolean conditions explicitly so the generated code matches your intent.