classification, which attempts to assign each input value to one of a given set of classes (for example, determine whether a given email is “spam” or “non-spam”).
regression, which assigns a real-valued output to each input;
sequence labeling, which assigns a class to each member of a sequence of values (for example, part of speech tagging, which assigns a part of speech to each word in an input sentence);
parsing, which assigns a parse tree to an input sentence, describing the syntactic structure of the sentence.