The authors believe that SVMs are a topic now sufficiently mature that it should be viewed as its own subfield of machine learning. SVMs, first introduced by Vladimir Vapnik, are a type of linear learning machines much like the famous perceptron algorithm and, thus, function to classify input patterns by first being trained on labeled data sets (supervised learning). However, SVMs represent a significant enhancement in function over perceptrons. The power of SVMs lies in their use of nonlinear kernel functions that implicitly map input into high-dimensional feature spaces. In the high-dimensional feature spaces, linear classifications are possible; they become nonlinear in the transformation back to the original input space.

Kernel functions can implicitly combine these two steps (nonlinear mapping and linear learning) into one step in constructing a nonlinear learning machine.