索引

1. Origins, structure, and basic meaning

• Structure: 索引 is read さくいん and is a noun for an organized list that lets readers find entries and their locations in a book or document.
• Basic usage: It is used to locate the pages where an unfamiliar term or a person's name appears.

2. Common pitfalls and similar expressions

• Distinguishing an index from a table of contents
  • Unlike a table of contents, which shows chapters in sequence, it helps readers locate information by entry.