I explain what is an unsupervised classification algorithm and what is a supervised algorithm. 
I use examples about remote sensing image classification and I discuss my opinion about the unsupervised algorithms, which are in fact similar to the supervised ones. 
Take as one example the well known unsupervised K-Means algorithm. The analyst must inform a priori the most important parameter to run the algorithm, the K value.
I have a video about the K-Means algorithm.
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The intro and the final sounds were recorded at my home, using an old clock that belonged to my grandmother.
Thanks for listening