# Blocks

> A piece of a page kept as its own document, so one header or one card design can appear in many places and be changed in exactly one.
>
> From the MightyBuilder documentation: https://docs.mightybuilder.ai/pages/blocks

A block is a piece of a page kept as its own document, so the same markup can
appear in several places and be changed in one.

## What it is for

A header, a footer, a call-to-action strip, the card design your blog index
repeats. Anything you would otherwise paste into six pages and then have to edit
six times.

A block has no address. It is never a page on your site — it only appears inside
the pages that embed it.

## Embedding one

```liquid
{% render "aB3x9kQ2mN01" %}
```

The name in quotes is the block's id, which you can copy from the block's own
screen. Ask for it in words — "put the opening hours block on the contact
page" — and the AI writes that line for you.

## Blocks are documents

They live under **Site → Blocks** in the rail, and they are the same kind of
thing as a page or a form: their own editor, their own drafts, their own
revisions, their own trash.

That means a block is published with everything else when you press Publish, and
a change to one block reaches every page that embeds it in the same release.

## A block in use cannot be taken down

If a document still embeds it, **disabling or trashing is refused** and you are
told which documents by name. Otherwise those pages would be left with a hole in
them, and the first you would hear of it is the live site.

Take the `{% render %}` tag out of them first, then take the block down. The
same rule protects a form.

## A fact you repeat belongs in a block

Your phone number appears in the header, the footer and the contact page.
Typed into each, changing it means finding them all. Written once in the footer
block that every page embeds, it is one edit — which is also how the AI keeps
it, and why "update our phone number" is one move.