---
title: "Topol Block"
description: "A Template reference of how the template is structured. This a useful information for building a custom block or editing templates in code."
url: https://docs.topol.io/email-editor/template-reference/block.html
---

# Topol Block

**`TopolBlock` is the base interface every block extends**, carrying the two fields common to all of them: the MJML `tagName` and a unique `uid`.

```ts
interface TopolBlock {
  tagName: string;
  uid: string;
}
```