# HtmlDocument guide
When you're using Cherrycake to build a web app, the [HtmlDocument](https://cherrycake.tin.cat/version-0.x/reference/core-modules/htmldocument) module helps you create standard HTML structure headers and footers with some additional useful capabilities.
The two most important methods of the [HtmlDocument](https://cherrycake.tin.cat/version-0.x/reference/core-modules/htmldocument) module are [HtmlDocument::header](https://cherrycake.tin.cat/version-0.x/reference/core-modules/htmldocument/htmldocument-methods#header) and [HtmlDocument::footer](https://cherrycake.tin.cat/version-0.x/reference/core-modules/htmldocument/htmldocument-methods#footer), they both take care of building the usual ` ...` and `...` tags. For example, take this code that outputs a simple HTML response to show a webpage:
```php
$e->Output->setResponse(new \Cherrycake\ResponseTextHtml([
"code" => \Cherrycake\RESPONSE_OK,
"payload" =>
$e->HtmlDocument->header().
"Hello world!".
$e->HtmlDocument->footer()
]));
```
This would output the following HTML code:
```markup
Hello world!
```
Take a look at the[ configuration of the HtmlDocument](https://cherrycake.tin.cat/version-0.x/reference/core-modules/htmldocument), where you can configure the title of your page, description, keywords, and many other important aspects of your HTML document structure.
> See how HtmlDocument also took care of including a CSS stylesheet and a JavaScript script automatically. This will come in handy when you start using the [CSS and Javascript modules](https://cherrycake.tin.cat/version-0.x/guide/css-and-javascript-guide).
## Common usage with Patterns
You might find quite helpful to use the [header](https://cherrycake.tin.cat/version-0.x/reference/core-modules/htmldocument/htmldocument-methods#header) and [footer](https://cherrycake.tin.cat/version-0.x/reference/core-modules/htmldocument/htmldocument-methods#footer) [HtmlDocument](https://cherrycake.tin.cat/version-0.x/reference/core-modules/htmldocument) methods in your HTML [patterns](https://cherrycake.tin.cat/version-0.x/guide/patterns-guide). Just call them at the beginning and at the end of your pattern and you'll get a complete HTML document.
For example, take a look at this HTML pattern named `home.html`:
```markup
HtmlDocument->header() ?>
Hello world!
HtmlDocument->footer() ?>
```
Now we parse it and send it to the user's browser with [Patterns::out](https://cherrycake.tin.cat/version-0.x/reference/core-modules/patterns/methods#out):
```php
$e->Patterns->out("home.html");
```
And we get exactly the same "Hello World!" HTML page as above.
Remembers to add the [HtmlDocument](https://cherrycake.tin.cat/version-0.x/reference/core-modules/htmldocument) module to your module's list of dependent core modules so it is available to use, like this:
```php
namespace CherrycakeApp\MyModule;
class MyModule extends \Cherrycake\Module {
protected $dependentCoreModules = [
"HtmlDocument"
];
...
}
```