An interviewer will ask you this question to learn about your ability to analyze existing applications and identify issues or improvement opportunities. Many developers are skilled at writing their own code but struggle when analyzing code written by somebody else. Programming is as much of an art as it is a science. Every developer has their own style and uses a different approach to creating software, even though they use the same language and platforms. When answering a question like this, you should be specific and provide an example to illustrate your answer.