Machine Learning in simple terms(not over simplified) is all about, making the system PREDICT & CONTROL , trained by a set of examples , is a subset of Artifical Intelligence & subsymbolic in nature. It is the corner stone of succesful e-commerce & Intelligent systems and Analytics. also it is the crux of Data science. ML, inturn depends on Statistics and computer Science..
Differences and similartes between DS , BigData & Machine Learning
Learning with trees
unsupervised Learning & Dimensionality reduction