Ensemble Methods: A Beginner's Guide

When I started my Data Science journey,few terms like ensemble,boosting often popped up.Whenever I opened the discussion forum of any Kaggle Competition or looked at any winner's solution,it was mostly filled with these things. At first these discussions sounded totally alien,and these class of ensemble models looked like some fancy stuff not meant for the newbies,but trust me once you have a basic understanding behind the concepts you are going to love them! So let's start with a very simple question,What exactly is ensemble? "A group of separate things/people that contribute to a coordinated whole" In a way this is kind of the core idea behind the entire class of ensemble learning! Well let's rewind the clocks a bit and go back to the school days for a while, remember you used to get a report card with an overall grade.Well how exactly was this overall grade calculated,your teachers of respective subjects gave some feedback based on their set of criteria,for example your math teacher would assess you on his own criteria like algebra,trigonometry etc, sports teacher would judge you how you perform on the field,your music teacher would judge on you vocal skills.Point being each of these teachers have their own set of rules of judging the performance of a student and later all of these are combined to give an overall grade on the performance of the student.