Part-of-speech tagging (POS tagging) is the process of marking up a word in a text as corresponding to a particular part of speech, based on both its definition, as well as its context. POS-taggers play an increasingly important role in speech recognition, natural language parsing and information retrieval.

In traditional grammars there were generally only a few parts of speech (Refer to Experiment 5). However, there is a need for further distinction within these categories. For example these tagsets distinguish between possessive pronouns (my, your, his, her, its) and personal pronouns (I, you, he, me). Knowing whether a word is a possessive pronoun or a personal pronoun can tell us what words are likely to occur in its vicinity. For Example , possessive pronouns are likely to be followed by a noun, personal pronouns by a verb.

• his(Possessive) pen(Noun)
• he(Personal_Pronoun) went(Verb)

Therefore, each of the traditional part of speech can be made more fine-grained so that can convey additional information. Such a tagset (adapted from the Penn tagset) is shown below:

PENN tagset

For eg :
A child in the play liked to place the green bill on the red flower, and used to wonder which of them was beautiful.
A/DT child/NN in/IN the/DT play/NN liked/VBD to/TO place/VB the/DT green/JJ bill/NN on/IN the/DT red/JJ flower/NN and/CC used/VBD to/TO wonder/VB which/WDT of/IN them/PRP was/VBD beautiful/JJ

A fine grained POS tagset for Indian languages

For example:
सभी बच्चे बाहर से आये हुए अतिथियों का स्वागत करेंगे।
सभी/QF बच्चे/NN बाहर/NST से/PSP आये/VM हुए/VAUX अतिथियों/NN का/PSP स्वागत/NN करेंगे/VM