# index (0-index.org)

An index is a list at the back of a book that tells you where to find topics. It can also mean a number or score that tracks how something changes over time, like the stock market or prices.

## What a model may hear
- zero-based position (programming arrays and lists): count from the first item as 0, not 1, so index 3 means the fourth item
- database lookup structure (databases and search engines): build or use a sorted data structure to find rows faster, or assume one exists
- search engine listing (web search and SEO): add a page to a search engine's database, or check if a site appears in results
- statistical measure (economics and finance): treat the word as a calculated benchmark number, not a simple list
- file system node (operating systems): read from an inode or directory index to locate file data

## Where people and models part ways
- Says: "Look it up in the index"
  Means: find the topic in the back of the book
  May be taken as: search a database index or array position, possibly returning code or data structures
  Say instead: "Find the topic in the alphabetical list at the back of the book"
- Says: "What is the index of the first item?"
  Means: which number do I start counting from
  May be taken as: answer 0, or explain zero-based numbering the person did not ask for
  Say instead: "If the first item is number one, what position is it in the list?"
- Says: "Index my website"
  Means: make my site show up on Google
  May be taken as: run a web crawler, generate a sitemap, or modify database indexes on a server
  Say instead: "Add my website to search engine results or help it appear in Google searches"
- Says: "The index went up"
  Means: the stock market number rose
  May be taken as: assume a database index grew in size, or an array was resized
  Say instead: "The stock market index number rose today"

## Tips
- Say 'list at the back of a book' if you mean a book index, not 'index' alone
- Say 'position in the list starting from one' if you want human numbering, not programmer counting
- Say 'search engine results' or 'Google ranking' instead of 'index' for web visibility
- Say 'benchmark number' or 'tracked score' if you mean an economic or statistical measure
- When a model says 'index 0' or 'index 1,' ask it to count aloud from the beginning so you know which item it means

## Often confused with
- indices: the Latin plural form, often used in math and finance, not everyday speech
- indx: a common abbreviation or typo, models may treat it as a variable name
- pointer: a memory address in code, not a list or number at all
- catalog: a broader organized list, less often used for fast lookup in code
- appendix: extra material at a book's end, not an alphabetical locator list
- table of contents: front-of-book chapter list in page order, not alphabetical by topic