---
title: Base templates and blocks
description: The base and block constructs allow you to define the outer shell of your master templates (i.e., the chrome of the page).
categories: [fundamentals,templates]
keywords: [blocks,base]
menu:
docs:
parent: templates
weight: 40
weight: 40
aliases: [/templates/blocks/,/templates/base-templates-and-blocks/]
toc: true
---
The `block` keyword allows you to define the outer shell of your pages' one or more master template(s) and then fill in or override portions as necessary.
{{< youtube QVOMCYitLEc >}}
## Base template lookup order
The base template lookup order closely follows that of the template it applies to (e.g. `_default/list.html`).
See [Template Lookup Order](/templates/lookup-order/) for details and examples.
## Define the base template
The following defines a simple base template at `_default/baseof.html`. As a default template, it is the shell from which all your pages will be rendered unless you specify another `*baseof.html` closer to the beginning of the lookup order.
{{< code file="layouts/_default/baseof.html" >}}
{{ block "title" . }}
<!-- Blocks may include default content. -->
{{ .Site.Title }}
{{ end }}
{{ block "main" . }}
{{ end }}
{{ block "footer" . }}
{{ end }}
{{< /code >}}
## Override the base template
From the above base template, you can define a [default list template][hugolists]. The default list template will inherit all of the code defined above and can then implement its own `"main"` block from:
{{< code file="layouts/_default/list.html" >}}
{{ define "main" }}
Posts
{{ range .Pages }}
{{ .Title }}
{{ .Content }}
{{ end }}
{{ end }}
{{< /code >}}
This replaces the contents of our (basically empty) "main" block with something useful for the list template. In this case, we didn't define a `"title"` block, so the contents from our base template remain unchanged in lists.
{{% note %}}
Code that you put outside the block definitions *can* break your layout. This even includes HTML comments. For example:
```go-html-template
{{ define "main" }}
...your code here
{{ end }}
```
[See this thread from the Hugo discussion forums.](https://discourse.gohugo.io/t/baseof-html-block-templates-and-list-types-results-in-empty-pages/5612/6)
{{% /note %}}
The following shows how you can override both the `"main"` and `"title"` block areas from the base template with code unique to your [default single page template][singletemplate]:
{{< code file="layouts/_default/single.html" >}}
{{ define "title" }}
{{ .Title }} – {{ .Site.Title }}
{{ end }}
{{ define "main" }}
{{ .Title }}
{{ .Content }}
{{ end }}
{{< /code >}}
[hugolists]: /templates/lists
[lookup]: /templates/lookup-order/
[rendering the section]: /templates/section-templates/
[singletemplate]: /templates/single-page-templates/