Circa is a programming language created by Andy Fischer, primarily aimed at facilitating rapid prototyping. The language features unique syntax elements, such as the @ operator, which serves as syntactic sugar for reassigning an identifier to the result of a statement. This operator allows for a more concise expression of commands, exemplified by two equivalent lines of code: "my_number = max(my_number, 40)" and "max(@my_number, 40)." Lists in Circa are denoted by square brackets and can have their elements separated by commas, semicolons, or spaces, providing flexibility in list formatting. The language's design offers intriguing concepts that make it an attractive option for developers interested in swift project iteration.