# Information retrieval built the machine that marketing talks about without reading its manual. Canonical: https://www.searchresultoptimization.com/information-retrieval/ Author: Johannes Faupel On this page **What it is** Information retrieval is the science of finding the document, and today the passage, that answers a need. **The problem until now** Its measures stayed inside the field, so nobody read their own pages the way a retrieval system reads them. **What you can do from here** You can see which passage of yours can be found, scored and taken, and what weakens it. ![Information retrieval: a page is split into passages, passages are scored for a query, the ranked list follows](https://www.searchresultoptimization.com/images/maps/passage-retrieval-information-retrieval.svg?v=1790368036) *Information retrieval: How the parts depend on each other.* ## Try this first Three tests, about ten minutes. They show your pages as a retrieval system sees them. Tests on this page you have run: 0 of 3. The count stays in this browser only. Test: Information retrieval - Take one heading of your page that is phrased as a question. - Read only the first sentence under it. - Think: does that sentence answer on its own? Whether a passage can be taken out and still work. Test - Search your topic and note the exact words the top results use. - Note what you got, before you open anything else. - Think: which of those words are missing from your page? The vocabulary a retrieval system counts. Test - Write down five facts of yours that should be findable. - Search each one with `site:example.com` and your own domain. - Think: how many were found? Your own recall, out of five. Search engines are engineering before they are marketing. The people who optimize search engines are the engineers who build them. ## Topics in this field [Learning to rank](https://www.searchresultoptimization.com/information-retrieval/learning-to-rank/): The system is trained on the behaviour it caused. [Snippet generation](https://www.searchresultoptimization.com/information-retrieval/snippet-generation/): It is written by a machine, from your text, for a query you did not know about. [Query expansion](https://www.searchresultoptimization.com/information-retrieval/query-expansion/): You are answering a question that was quietly edited before it reached you. [Relevance feedback](https://www.searchresultoptimization.com/information-retrieval/relevance-feedback/): Absence produces no signal. [Query performance prediction](https://www.searchresultoptimization.com/information-retrieval/query-performance-prediction/): A page of ten results looks the same whether the answer exists or not. [Passage retrieval](https://www.searchresultoptimization.com/information-retrieval/passage-retrieval/): Your page is being read in fragments by a system that never sees the whole. [Mean average precision](https://www.searchresultoptimization.com/information-retrieval/mean-average-precision/): A score of 0.87 tells you how well the ranking matched a list somebody wrote down. [Vector space model](https://www.searchresultoptimization.com/information-retrieval/vector-space-model/): If the web never described your case, the vector for it is somebody else's. [Inverted index](https://www.searchresultoptimization.com/information-retrieval/inverted-index/): The web is the part of knowledge that somebody bothered to publish and a crawler managed to reach. [Precision and recall](https://www.searchresultoptimization.com/information-retrieval/precision-and-recall/): The two measures behind every search evaluation, what they cannot see, and who decided what counts as relevant. [Latent semantic analysis (LSA)](https://www.searchresultoptimization.com/information-retrieval/latent-semantic-analysis-lsa/): Latent semantic analysis builds meaning from nothing but word counts. [Controlled vocabulary](https://www.searchresultoptimization.com/information-retrieval/controlled-vocabulary/): A controlled vocabulary fixes which word stands for which concept. These pages state what each mechanism does, and then the part that matters to anyone who publishes on the web. ![A blurred search engine result page](https://www.searchresultoptimization.com/images/search-result-serp.webp?v=1648967210) *A result page presents a fraction of what exists. The fraction is the product.* ## The other fields - [Digital marketing](https://www.searchresultoptimization.com/digital-marketing/) - [Human-computer interaction](https://www.searchresultoptimization.com/human-computer-interaction/) - [Computational linguistics](https://www.searchresultoptimization.com/computational-linguistics/) - [Social epistemology](https://www.searchresultoptimization.com/social-epistemology/) ## Everything in this field, on one screen Each point is a page of information retrieval. Drag, zoom, and click a point to open that page. The whole site is drawn on the [knowledge graph](https://www.searchresultoptimization.com/knowledgegraph/). [See this field inside the whole site →](https://www.searchresultoptimization.com/knowledgegraph/)