The creator of extreme programming, Kent Beck mentioned the emphasis of design quality while developing software in the late 1990s and the use of the term Code Smells. This term became a commonly used word in programming after it was featured in the book Refactoring: Improving the Design of Existing Code by Martin Fowler, a renowned software scientist who popularized the practice of code refactoring. Code smells are not bugs or errors. Instead, these are absolute violations of the fundamentals of developing software that decrease the quality of code.