related posts in the previous we have learned how to find classes or categories of individual data points with handful of training data items that were paired with their respective classeswe learned model that we can now use to classify future data items we called this supervised learningas the learning was guided by teacherin our case the teacher had the form of correct classifications let us now imagine that we do not possess those labels by which we could learn the classification model this could befor examplebecause they were too expensive to collect what could we have done in that casewellof coursewe would not be able to learn classification model stillwe could find some pattern within the data itself this is what we will do in this where we consider the challenge of "question and answerwebsite when user browses our site looking for some particular informationthe search engine will most likely point him/her to specific answer to improve the user experiencewe now want to show all related questions with their answers if the presented answer is not what he/she was looking forhe/she can easily see the other available answers and hopefully stay on our site the naive approach would be to take the postcalculate its similarity to all other postsand display the top most similar posts as links on the page this will quickly become very costly insteadwe need method that quickly finds all related posts