title: Natural language processing: an introduction.
abstract: OBJECTIVE
  To provide an overview and tutorial of natural language processing (NLP) and modern NLP-system design.
  
  
  BACKGROUND
  This tutorial targets the medical informatics generalist who has limited acquaintance with the principles behind NLP and/or limited knowledge of the current state of the art.
  
  
  METHODS
  We describe the historical evolution of NLP, and summarize common NLP sub-problems in this extensive field. We then provide a synopsis of selected highlights of medical NLP efforts. After providing a brief description of common machine-learning approaches that are being used for diverse NLP sub-problems, we discuss how modern NLP architectures are designed, with a summary of the Apache Foundation's Unstructured Information Management Architecture. We finally consider possible future directions for NLP, and reflect on the possible impact of IBM Watson on the medical field.
authors.affiliation: Yale University School of Medicine, New Haven, Connecticut, USA. prakash.nadkarni@yale.edu
authors.forename: Prakash M
authors.initials: PM
authors.lastname: Nadkarni
authors.forename: Lucila
authors.initials: L
authors.lastname: Ohno-Machado
authors.forename: Wendy W
authors.initials: WW
authors.lastname: Chapman
mesh_terms: D006801:Humans; D019451:Information Management; D016247:Information Storage and Retrieval; D008490:Medical Informatics / Q000639:trends*; D008962:Models, Theoretical; D009323:Natural Language Processing; D010363:Pattern Recognition, Automated; D014584:User-Computer Interface