Aside from being a buzzword, data mining is the analysis step from Knowledge Discovery in Databases (KDDs), which is concerned with uncovering hidden patterns from huge unstructured datasets. The term data mining doesn't define a single method, but a broad collection of used methods. Those methods range from linear regressions and clustering techniques, all the way to visualizations, random forests, and artificial intelligence methods.
You may have already noticed, but it's not that easy to set apart what data mining ...