An arithmetic expression contains operators and operands, along with constants and operations. It can take three forms: prefix, infix, or postfix. In prefix form, the operator comes before the operands. In infix form, the operator is between the operands. And in postfix form, the operator follows the operands. The main advantages of arithmetic expressions are that they are easier to evaluate, require fewer brackets, and are fast to calculate. However, they are sensitive to extreme values and not suitable for time series data.