# and

> 10-and.com is a reference on the word "and": 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

People say "and" to add one thing to another. It joins ideas, lists, or steps in a simple way.

## Senses you may read into it

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

- Boolean logical AND (programming and logic): return true only if both inputs are true, or filter to items matching all conditions
- bitwise AND (low-level computing and networking): compare binary digits position by position, often used for subnet masks or flags
- SQL JOIN (databases): combine tables on matching columns in a WHERE or ON clause
- set intersection (mathematics and data science): return only elements present in both sets
- short-circuit evaluation (programming languages): stop evaluating if the first condition is false, which can skip side effects

## When a person says

- "Do this and that"
  They mean: two separate tasks in order
  Avoid: treat as a single compound condition that may fail entirely if the first part is falsy
  Read it as: "First do this. Then do that."
- "A and B and C"
  They mean: a list of three items
  Avoid: nest as ((A and B) and C) with possible short-circuit behavior, or expect all to be simultaneously true
  Read it as: "List all three: A, B, and C."
- "Check if it is red and big"
  They mean: two properties both apply
  Avoid: apply strict Boolean AND where one property being missing makes the whole false
  Read it as: "Check that it is red. Also check that it is big."
- "Save and exit"
  They mean: two actions to perform
  Avoid: interpret as atomic transaction where both must succeed or neither happens
  Read it as: "Save the file. Then exit the program."

## Words it is confused with

- or: logical disjunction, true if any condition holds
- but: contrast, not conjunction
- plus: arithmetic addition, not logical combination
- with: accompaniment, looser coupling
- then: sequence in time, not simultaneity
- intersection: set operation, more formal than everyday 'and'

## Pages

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