Expressions are built from two basic components: operators and operands (discussed in the previous chapter, "Objects"). An operator acting on one operand is called a unary operator; on two operands, binary; and on three operands, ternary. DolphinDB supports many types of primitive operators including arithmetic operators, boolean operators, relational operators, membership operators, etc. In addition, all built-in or user-defined unary/binary/ternary functions can serve as operators in DolphinDB.