Siksha Sarovar

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Siksha Sarovar is a free e-learning platform for coding courses, BCA university notes and competitive exam preparation. Optional Google sign-in saves your learning progress across devices.

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Unit 1 — Introduction to NLP: Scope, Challenges & Applications

Lesson 2 of 39 in the free Natural Language Processing notes on Siksha Sarovar, written by Rohit Jangra.

Introduction to Natural Language Processing

Natural Language Processing (NLP) is the branch of Artificial Intelligence concerned with enabling computers to read, understand, interpret, and generate human (natural) language — as opposed to a formal/programming language.

NLP sits at the intersection of Computer Science, Linguistics, and Artificial Intelligence.

Scope of NLP

NLP broadly covers two directions:

DirectionMeaningExamples
Natural Language Understanding (NLU)Machine interprets meaning from text/speechIntent detection, sentiment analysis, question answering
Natural Language Generation (NLG)Machine produces text/speech from data or meaningChatbot replies, auto-summaries, report generation

Why NLP is Hard — Core Challenges

  1. Ambiguity — the single biggest challenge in NLP, occurring at every level:
  • Lexical ambiguity: "bank" (river bank vs financial bank)
  • Syntactic ambiguity: "I saw the man with a telescope" (who has the telescope?)
  • Semantic ambiguity: "The chicken is ready to eat" (ready to eat, or ready to be eaten?)
  • Referential ambiguity: "Riya told Zoya that she passed" (who is "she"?)
  1. Context dependence — the same sentence can mean different things in different situations.
  2. Idioms and figurative language — "kick the bucket" does not mean literally kicking a bucket.
  3. World knowledge / common sense — "The trophy doesn't fit in the suitcase because it is too big" requires knowing what "it" refers to.
  4. Variability of language — spelling variations, slang, code-mixing (e.g. Hinglish), typos, sarcasm.
  5. Language diversity — thousands of languages and dialects, most with limited digital resources (low-resource languages).
  6. Segmentation problems — some languages (e.g. Chinese) have no explicit word boundaries.
  7. Scale and evolving vocabulary — new words, hashtags, and abbreviations appear constantly on social media.
# Lexical ambiguity example
sentence1 = "I deposited money in the bank."     # financial institution
sentence2 = "We sat by the bank of the river."   # river bank
# Same word "bank" -> two entirely different meanings

Applications of NLP

CategoryExamples
Search & Information RetrievalGoogle Search, semantic search, autocomplete
Text ClassificationSpam filtering, sentiment analysis, topic tagging
Conversational AIChatbots, virtual assistants (Alexa, Siri, Google Assistant)
Machine TranslationGoogle Translate, DeepL
Information ExtractionResume parsing, extracting entities from contracts
SummarizationNews digest apps, meeting-notes summarizers
SpeechSpeech-to-text, text-to-speech
Generative AIChatGPT-style assistants, content generation, code generation
# A tiny taste of what NLP enables — sentiment in one line (conceptually)
text = "The delivery was late but the product quality is excellent."
# An NLP pipeline would say: mixed sentiment, slightly positive overall

We will build toward all of these applications across the four units of this course.