# Entity-Relationship Diagram (ERD)

*noun*

say it: **“EE-ar-DEE”** **/ˌiː ɑːr ˈdiː/**

A picture of a database showing its tables as boxes and the relationships between them as lines.

## What is **Entity-Relationship Diagram (ERD)**?

**Entity-Relationship Diagram (ERD)** — A picture of a database. Each table is a box listing its columns, and lines join tables that are related through their keys, such as Orders to Customers. It shows the whole design at a glance.

## In a sentence

- “The **ERD** showed that every order points to one customer through CustomerID.”

Level: Apprentice · [More Database terms at this level](https://www.ask-codey.com/glossary?category=database&level=2)

Updated: October 28, 2026

Source: https://www.ask-codey.com/glossary/entity-relationship-diagram-erd