Overview of Unsupervised Machine Learning Tasks & Applications

Although most of the applications of Machine Learning in our world are based on supervised machine learning algorithms and that's why this is where most of the investment goes into this direction. However, the majority of the available data is actually unlabeled: we have the input feature X, but we do not have the labels y. From here comes the importance of unsupervised learning. Yann LeCun famously said:

If intelligence was a cake, unsupervised learning would be the cake, supervised learning would be the icing on the cake…