tiptap/docs/src/docPages/api/marks/underline.md

# Underline
Use this extension to render text <u>underlined</u>. If you pass `<u>` tags, or text with inline `style` attributes setting `text-decoration: underline` in the editor’s initial content, they all will be rendered accordingly.

Be aware that underlined text in the Internet usually indicates that it’s a clickable link. Don’t confuse your users with underlined text.

::: warning Restrictions
The extension will generate the corresponding `<u>` HTML tags when reading contents of the `Editor` instance. All text marked underlined, regardless of the method will be normalized to `<u>` HTML tags.
:::

## Installation
```bash
# with npm
npm install @tiptap/extension-underline

# with Yarn
yarn add @tiptap/extension-underline
```

## Settings
| Option         | Type     | Default | Description                                                           |
| -------------- | -------- | ------- | --------------------------------------------------------------------- |
| HTMLAttributes | `Object` | `{}`    | Custom HTML attributes that should be added to the rendered HTML tag. |

## Commands
| Command   | Parameters | Description              |
| --------- | ---------- | ------------------------ |
| underline | —          | Mark text as underlined. |

## Keyboard shortcuts
* Windows/Linux: `Control`&nbsp;`U`
* macOS: `Cmd`&nbsp;`U`

## Source code
[packages/extension-underline/](https://github.com/ueberdosis/tiptap-next/blob/main/packages/extension-underline/)

## Usage
<demo name="Marks/Underline" highlight="3-5,17,36" />