# Entities in Common Data Service

A Common Data Service _Database_ is **one instance** of a Common Data Service which stores data in **standard and custom structures** which we call **entities**.

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In other words **Standard/Custom Structure that stores data = Entities** (in CDS)

Formal: An **entity** is defined as a **logical set of records used to store data**.
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Entities are similar to _tables_ in a _relational database_, but with entities you can create many different fields around one topic (like having different rows of information under a sub-heading).

So you can create many different instances of a Common Data Service (create many different CDS databases) to host data for your solution. **When you create a Common Data Service**, the database by default **automatically fills in some standard entities to store data**. This is common across the board - but you can extend upon this to customise your database.



