Table 1:

Common preprocessing stages of natural language processing with definition and examples.

NLP Stage	Definition	Example
Tokenization	Breaking text down into its components	The kidney helps the body maintain homeostasis. --> The | kidney | helps | the | body | maintain | homeostasis.
Remove stop words	Removing common words (e.g. “the”, “a”, “and”) that do not provide information	the | kidney | helps | the | body | maintain | homeostasis --> | kidney | helps | body | maintain | homeostasis
Part of speech tagging	Assigning a grammatical role to a word used in a sentence. These are generally: noun, pronoun, adjective, verb, adverb, preposition, conjunction, interjection	kidney: noun helps: verb body: noun maintain: verb homeostasis: noun
Stemming/lem matization	Reducing inflected or derived words into their stem words or base words	kidney: kidney helps: help body: body maintain: maintain homeostasis: homeostasis
Named-entity recognition	Identify and locate named entities such as names, organization, and locations.	Belding Hibbard Scribner (Person) was an American (Location) physician and a pioneer in kidney dialysis.
Negation detection	The task of determining the presence of absence of a finding.	Mrs. Nephron did not (negation detection) require dialysis.