This paper introduces the concept of symbolic execution, a method for testing and debugging programs by supplying symbolic inputs instead of normal values. Symbolic execution allows a single symbolic execution to represent a large class of normal executions, making it more efficient than traditional testing methods. The paper discusses the challenges and issues in symbolic execution, particularly during conditional branch statements, and presents EFFIGY, an interactive symbolic execution system. EFFIGY provides features such as debugging, testing, and program verification, and can handle symbolic expressions and path conditions. The paper also explores the relationship between symbolic execution and program proving, showing how symbolic execution can be used to prove program correctness. The author concludes that symbolic execution is a valuable tool for program testing and debugging, offering significant improvements over traditional methods.This paper introduces the concept of symbolic execution, a method for testing and debugging programs by supplying symbolic inputs instead of normal values. Symbolic execution allows a single symbolic execution to represent a large class of normal executions, making it more efficient than traditional testing methods. The paper discusses the challenges and issues in symbolic execution, particularly during conditional branch statements, and presents EFFIGY, an interactive symbolic execution system. EFFIGY provides features such as debugging, testing, and program verification, and can handle symbolic expressions and path conditions. The paper also explores the relationship between symbolic execution and program proving, showing how symbolic execution can be used to prove program correctness. The author concludes that symbolic execution is a valuable tool for program testing and debugging, offering significant improvements over traditional methods.