# set

> Assign a value or captured markup to a variable.

`set` assigns a value to a variable.

page.kiln:

```kiln
{% set title = page.title ?? "Untitled" %}
<h1>{{ title }}</h1>
```

Output:

```html
<h1>Untitled</h1>
```

## Capturing markup

The block form renders its content and stores the result. Use it to build a piece of markup once and output it in several places.

page.kiln:

```kiln
{% set logo %}<a href="/" class="logo">{{ site.name }}</a>{% endset %}

<header>{{ logo }}</header>
<footer>{{ logo }}</footer>
```

Output:

```html
<header><a href="/" class="logo">Acme</a></header>
<footer><a href="/" class="logo">Acme</a></footer>
```

The captured markup is already escaped, so it isn't escaped again when you output it.

## Where variables live

`set` updates a variable in the scope where it already exists, or creates it in the current scope. See [Variables and scope](https://kilnlang.com/docs/language/variables/).

In a page that extends a layout, top-level `set` tags run before the layout renders, so the layout and every block can use them.