Teaching to machines: What is learning in machine learning entails?

Machine Learning (ML) is now a de-facto skill for every quantitative job and almost every industry embraced it, even though fundamentals of the field is not new at all. However, what does it mean to teach to a machine? Unfortunately, for even moderate technical people coming from different backgrounds, answer to this question is not apparent in the first instance. This sounds like a conceptual and jargon issue, but it lies in the very success of supervised learning algorithms. What is a machine in machine learning First of all here, machine does not mean a machine in conventional sense, but computational modules or set of instructions.