# What is the “Hello World” problem of Unsupervised Learning?

As a followup to this question, I'm interested in what the typical "Hello World" problem (first easy example problem) is for unsupervised learning.

• Probably knmeans clustering or gaussian clustering – FourierFlux Sep 14 at 6:32
• @FourierFlux Both seem to be solution methods, not problems. Do I understand correctly that problems would be: cluster $n$ training observations in a $d$-dimentsional space, then apply those clusters to new observations? – Christian Aichinger Sep 14 at 6:45