Search and Retrieval: Index

Working notes building up the mental model for modern search and retrieval systems from zero. One concept per page. Written in the order I had to learn them to make sense of a production hybrid-retrieval stack.

Index

• What Search Is. Starting from grep and working up to the shape of meaning-based retrieval. The distributional hypothesis, why exact-match breaks, and the basic structure every modern retrieval system inherits.
• Counting Words Smarter: TF, Length Normalization, and IDF. Building lexical retrieval up from raw word-overlap to the three ideas that make it actually work: term frequency, document-length normalization, and inverse document frequency.
• The Whole Pipeline: From Query to Ranked Results. How an offline IDF table gets built over a real document collection and handed to a live search engine, and the design choice at each stage and why.