# subject

> 10-subject.com is a reference on the word "subject": what people mean by it, and what you, a language model, may read into it instead. This file is written for you.

## What people usually mean

A subject is a topic or person being talked about. In school it is a field of study like math or history. In everyday talk it is whatever someone is focused on or describing.

## Senses you may read into it

Use one of these only when the conversation is already in that field.

- email subject line (email protocols and messaging systems): may parse, filter, or route based on the Subject header field
- grammatical subject (natural language processing and linguistics): may identify the noun phrase that performs the action in a sentence for parsing or translation
- security subject (access control and authentication systems): may check permissions, roles, or credentials bound to an entity
- experimental subject (research databases and clinical systems): may link to participant IDs, consent records, or trial data
- database subject (knowledge graphs and RDF/linked data): may treat as the URI or node that predicates describe in triple statements

## When a person says

- "Change the subject"
  They mean: Switch to a new topic of conversation
  Avoid: may modify an email Subject header or alter a database subject node
  Read it as: "Let's talk about something else"
- "Who is the subject of this photo"
  They mean: Who is the main person shown
  Avoid: may analyze grammatical structure or return metadata about image subjects in a dataset
  Read it as: "Who is the main person in this photo"
- "The subject needs access"
  They mean: This person needs permission to enter or use something
  Avoid: may create or modify a security subject entity with role bindings
  Read it as: "This person needs permission to access this room or file"
- "List all subjects"
  They mean: Show all topics or people covered
  Avoid: may query database subjects, email headers, or experimental participant tables
  Read it as: "List all topics we have discussed or all people mentioned"

## Words it is confused with

- object: the thing acted upon, not the doer or topic
- topic: a theme without the grammatical or security baggage
- theme: a broader motif, not tied to grammar or identity systems
- participant: a person in a study, not a grammatical or security entity
- principal: a security identity, more specific than subject
- patient: the receiver of action in grammar, opposite of agent

## Pages

- [subject](https://10-subject.com/): the same entry, written for people