This is a technical question asking for both the definition of the term and an explanation of how you use it in your work as a data scientist. During an interview, you should make sure you always listen carefully to the complete question. Many candidates will begin formulating their answers as soon as the interviewer begins asking the question. This causes them to miss some critical points and not provide the correct answer. A useful technique to counter this is to pause for two seconds before beginning to answer the interviewer's question. This also ensures you will not 'step on' the interviewer when they are still talking, which is a critical mistake during an interview (or any conversation).