1. A method of identifying phrases in an electronic document comprising: identifying one or more phrase candidates in the electronic document; selecting one of the phrase candidates; numerically representing features of the selected phrase candidates to obtain a numeric feature representation associated with that phrase candidate by: identifying, from a predetermined dictionary map which maps words to unique numbers, the number associated with each word in the selected phrase candidate; and including the identified number associated with each word in the numeric feature representation; inputting the numeric feature representation into a machine learning classifier, the machine learning classifier being configured to determine, based on each numeric feature representation, that the phrase candidate associated with that numeric feature representation is a phrase, wherein identifying phrase candidates in the electronic document comprises identifying word level n-grams in the document; and associating the electronic document with a label identifying the subject matter of the electronic document, wherein the label is based on the phrase.