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---
layout: web
title: A Quick Guide to Modern HTML
---
# A Quick Guide to Modern HTML
> This guide is a work in progress!
Modern HTML is a remarkably simple and coherent standard.
## Semantic
- [`<html>`][html]: The root of an HTML document.
- There should exist one and only one `<html>` element in a document.
- [`<body>`][body]: The content of an HTML document.
- There may only exist one `<body>` element in a document.
- [`<h1>, <h2>, <h3>, <h4>, <h5>, <h6>`][heading elements]: Various heading elements.
- [`<p>`][p]: A paragraph. Text should typically be wrapped in a `<p>`.
- [`<hr/>`][hr]: A thematic break. Typically styled as a horizontal rule.
- [`<br/>`][br]: A line break.
- [`<wbr/>`][wbr]: A word break *opportunity*.
- Browsers will prefer breaking there when necessary. This is useful for ex. German and other languages with long words.
<details>
<summary>default styles</summary>
```css
html {
display: block;
}
```
```css
body {
display: block;
margin: 8px;
}
```
```css
h1, h2, h3, h4, h5, h6 {
display: block;
font-weight: bold;
}
h1 {
font-size: 2em;
margin-block: .67em;
}
h2 {
font-size: 1.5em;
margin-block: .83em;
}
h3 {
font-size: 1.17em;
margin-block: 1em;
}
h4 {
font-size: 1.00em;
margin-block: 1.33em;
}
h5 {
font-size: 0.83em;
margin-block: 1.67em;
}
h6 {
font-size: 0.67em;
margin-block: 2.33em;
}
```
```css
p {
display: block;
margin-block: 1em;
}
```
```css
hr {
display: block;
color: gray;
border: 1px inset;
margin-block: 0.5em;
margin-inline: auto;
overflow: hidden;
}
```
```css
br {
display-outside: newline;
}
```
```css
wbr {
display-outside: break-opportunity;
}
```
</details>
- [`<main>`][main]: The main content of the body of a document.
- There should exist at most one visible `<main>` element in a document.
- [`<header>`][header]: A section of a document intended for treatment as a header.
- [`<footer>`][footer]: A section of a document intended for treatment as a footer.
- [`<aside>`][aside]: A portion of a document only indirectly related to the main content.
- [`<article>`][article]: A self-contained composition within a document.
- [`<nav>`][nav]: A section of the document that provides navigation links.
- [`<section>`][section]: A generic standalone section of the document.
- [`<div>`][div]: The generic block container. `display: block`.
- [`<span>`][span]: The generic inline container. `display: inline` (default).
<details>
<summary>default styles</summary>
```css
main, section, aside, header, footer, article, nav, div {
display: block;
}
span {
/* display: inline; */
}
```
</details>
## Stylistic
- [`<b>`][b] or [`<strong>`][strong]: <b>bold</b> text
- [`<i>`][i] or [`<em>`][em]: <i>italic</i> text
- [`<u>`][u]: <u>underlined</u> text
- [`<s>`][s]: <s>struckthrough</s> text
- [`<q>`][q]: <q>quoted</q> text
- [`<small>`][small]: <small>small</small> text
- [`<sub>`][sub]: <sub>sub</sub>text
- [`<sup>`][sup]: <sup>super</sup>text
- [`<code>`][code]: <code>text styled like code</code>
- [`<pre>`][pre]: <pre style="display: inline; font-size: 0.8em;">preformatted text</pre>
<details>
<summary>default styles</summary>
```css
b, strong {
font-weight: bolder;
}
```
```css
i, em {
font-style: italic;
}
```
```css
u {
text-decoration: underline;
}
```
```css
s {
text-decoration: line-through;
}
```
```css
q:before {
content: open-quote;
}
q:after {
content: close-quote;
}
```
```css
small {
font-size: smaller;
}
```
```css
sub {
vertical-align: sub;
font-size: smaller;
}
```
```css
sup {
vertical-align: super;
font-size: smaller;
}
```
```css
code {
font-family: monospace;
}
```
```css
pre {
display: block;
font-family: -moz-fixed;
white-space: pre;
margin-block: 1em;
}
```
</details>
## Metadata
Several HTML elements provide *metadata* about the document in question. They are invisible and removed from the render tree (`display: none`), and only serve to provide information to the browser.
- [`<head>`][head]: The document metadata container.
- There should exist one and only one `<head>` element in a document.
- [`<title/>`][title]: The title of the document to be displayed.
- [`<base href="" target=""/>`][base]: the base URL for all relative URLs to use.
- There should exist no more than one `<base>` element in a document.
- [`<link .../>`][link]: Establishes relationships between the current document and other external resources.
- This is used for a variety of purposes: site icons, external stylesheets, ...
- [`<meta .../>`][meta]: Generic metadata.
- [`<style ...>`][style]: Generic metadata.
- [`<script ...>`][script]: Generic metadata.
<details>
<summary>default styles</summary>
```css
head, title, base, link, meta, style, script {
display: none;
}
```
</details>
```css
<style>
</style>
```
```css
<script>
</script>
```
`<template>`, `<slot>`
## Content
So far, the HTML elements we have looked at have been purely semantic, and devoid of actual content.
- [`<a href="" rel="" type="" target="" download="">`][a]: An external link to arbitrary content.
- [`<img src="" width="" height="" alt="" .../>`][img]: Embedded image content.
- [`<audio src="" ...>`][audio]: Embedded audio content.
- [`<video src="" width="" height="" ...>`][video]: Embedded video content.
- [`<track src="" ...>`][track]: Subtitles for audio/video content.
- [`<canvas width="" height="">`][canvas]: A target for drawing interactive graphics.
- [`<iframe width="" height="" ...>`][iframe]: Embedded arbitrary HTML content.
<details>
<summary>default styles</summary>
```css
a {
color: #0000EE;
text-decoration: underline;
cursor: pointer;
}
```
```css
img {
/* object-fit: fill; */
}
```
```css
video {
object-fit: contain;
}
```
```css
iframe {
border 2px inset;
}
```
</details>
## Lists
HTML supports *ordered* and *unordered* lists.
- [`<ul>`][ul]: An *unordered* list. Displayed with bullet points by default.
- [`<ol type="a" start=1 reversed>`][ol]: An *ordered* list. Displayed as a numbered list by default.
- [`<li value=1>`][li]: A *list element*. Nested within either `<ul>` or `<ol>`.
<details>
<summary>default styles</summary>
```css
li {
display: list-item;
text-align: match-parent;
}
```
```css
ul, menu {
display: block;
counter-reset: list-item;
margin-block: 1em;
padding-inline-start: 40px;
list-style-type: disc;
}
```
```css
ol {
display: block;
counter-reset: list-item;
margin-block: 1em;
padding-inline-start: 40px;
list-style-type: decimal;
}
```
</details>
Both ordered and unordered lists should have only `<li>`s as their directly nested elements.
On ordered lists, the `type` attribute indicates the numbering type, and can be one-of `a` (lowercase letters), `A` (uppercase letters), `i` (lowercase Roman numerals), `I` (uppercase Roman numerals), or `1` (Arabic numerals, default). The `start` attribute indicates the ordinal at which to start labeling at, and must be an Arabic numeral, even when `type` is not the default. The presence of the `reversed` attribute indicates that a list should be labelled in descending order. As usual, these properties all may be overridden with targeted CSS.
Within ordered lists, the `value` attribute on an `li` indicates that the ordering should jump to the specified ordinal and continue from there. Like `start`, it takes an Arabic numeral, irrespective of ordering style.
There are also a third type of lists available: *description lists*. These do not use the `<li>` element and are generally left unused. We discuss them in a future section.
## Hypertext
- [`<form ...>`][form]: A section that can perform interactive HTTP requests.
- [`<button ...>`][button]: An interactive element to be activated by the user.
- [`<input .../>`][input]: An interactive element that takes user input.
- [`<textarea ...>`][textarea]: An interactive element for multi-line user input.
- [`<label for="idx">`][label]: A label for an element (typically `<input>`) in a user interface.
- [`<meter ...>`][meter]: A fractional/scalar value within a known range.
- [`<select ...>`][select]: An interactive element that provides a list of options.
- [`<option label="" value="" selected disabled>`][option]: A menu option within a `<select>`.
- [`<optgroup label="" disabled>`][optgroup]: A grouping of options within a `<select>`.
<details>
<summary>default styles</summary>
```css
form {
display: block;
}
```
```css
button {
letter-spacing: initial;
word-spacing: initial;
line-height: initial;
text-transform: initial;
text-indent: initial;
text-shadow: initial;
text-align: center;
display: inline-block;
box-sizing: border-box;
}
```
```css
input {
letter-spacing: initial;
word-spacing: initial;
line-height: initial;
text-transform: initial;
text-indent: initial;
text-shadow: initial;
text-align: initial;
}
```
```css
input[type="button"], input[type="reset"], input[type="submit"], {
text-align: center;
}
```
```css
input[type="button"], input[type="checkbox"], input[type="color"], input[type="file"],
input[type="image"], input[type="radio"], input[type="reset"], input[type="search"], input[type="submit"] {
box-sizing: border-box;
}
```
```css
input[type="button"], input[type="color"], input[type="reset"], input[type="submit"] {
display: inline-block;
}
```
```css
input[type="hidden"] {
display: none !important;
}
```
```css
textarea {
letter-spacing: initial;
word-spacing: initial;
line-height: initial;
text-transform: initial;
text-indent: initial;
text-shadow: initial;
text-align: initial;
box-sizing: border-box;
white-space: pre-wrap;
}
```
```css
select {
letter-spacing: initial;
word-spacing: initial;
line-height: initial;
text-transform: initial;
text-indent: initial;
text-shadow: initial;
text-align: initial;
box-sizing: border-box;
}
```
</details>
## Assorted
There are various assorted HTML elements that don't neatly fit into a particular category.
- [`<details name="" open>`][details]
- [`<summary>`][summary]: A caption for a corresponding `<details>` element.
- [`<map name="">`][map]: Defines an image map with `<area>` for an `<img>`.
- [`<area>`][area]: Defines clickable areas within a `<map>` element.
- [`<noscript>`][noscript]
- [`<dialog open>`][dialog]
- [`<marquee ...>`][marquee]
Okay. That's everything important. 75 tags or so? I dunno. Manageable!
---
## Tables
- [`<table>`][table]: A table. Structured data.
- [`<thead>`][thead]: A row of cells acting as a header.
- [`<tbody>`][tbody]: The cells that compose the body of the table.
- [`<tfoot>`][tfoot]: A row of cells acting as a footer.
- [`<tr>`][tr]: A row of cells.
- [`<td colspan=1 rowspan=1 headers="">`][td]: Data cells. `colspan` and `rowspan` indicate their size in the table. `headers` indicates the ids of the corresponding header cells.
- [`<th scope="" colspan=1 rowspan=1 headers="">`][th]: Header cells. `colspan` and `rowspan` indicate their size in the table. `headers` indicates the ids of the corresponding header cells. `scope` may be one-of `row`, `col`, `rowgroup`, `colgroup`, and indicates the set of cells the header corresponds to.
- [`<col span=1>`][col]: A column within a table. Columns span over atop rows.
- [`<colgroup span=1>`][colgroup]: A group of columns within a table.
- [`<caption>`][caption]: The title of a table.
The sheer quantity of tags for tables is quite intimidating.
In general, tables are *far* less used than they once were, thanks to improvements in the layout capabilities of CSS.
You can pretty much just ignore them.
## Less Useful Elements
- [`<fieldset form="" name="" disabled>`][fieldset]: A grouping of controls within a `<form>`.
- [`<legend>`][legend]: A caption for a corresponding `<fieldset>` element.
- [`<output name="" form="id" for="ida idb...">`][output]:
An element into which the result of a user action is to be injected.
- [`<figure>`][figure]: A wrapper for some arbitrary self-contained content.
- [`<figcaption>`][figcaption]: An optional caption for a corresponding `<figure>`.
- [`<picture>`][picture]: Embedded image content. Contains multiple `<source>` elements and a fallback `<img>`.
- [`<source/>`][source]: A media resource for a `<picture>`, `<audio>`, or `<video>` element.
- [`<dl>`][dl]: A *description list*. Consists of terms (`<dt>`) and descriptions (`<dd>`). Ugly as sin, and scarcely used.
- [`<dt>`][dt]: Specifies a *term* entry in a description list.
- [`<dd>`][dd]: Specifies a *description* entry in a description list.
- [`<address>`][address]: An element indicating its contents are contact information.
- [`<blockquote cite="url">`][blockquote]: An element indicating its contents are an extended quotation.
- [`<data value="data">`][data]: An element indicating its content has corresponding data, in the `value` attribute.
- [`<search>`][search]:
An element indicating its contents are related to searching.
- [`<time datetime="">`][time]:
An element indicating a specific time. `datetime` must be set to a machine-readable format.
## Deprecation Fodder
These elements are *really* useless. You shouldn't bother knowing them. They're in the spec, but scarcely used.
- [`<abbr>`][abbr]: An element for displaying abbreviations.
- [`<cite>`][cite]: An element indicating its contents are a citation.
- [`<del>`][del]: An element for displaying deleted text.
- [`<dfn>`][dfn]: An element indicating its contents are a definition.
- [`<ins>`][ins]: An element for displaying inserted text.
- [`<kbd>`][kbd]: An element for displaying keyboard shortcuts.
- [`<mark>`][mark]: An element for displaying highlighted text.
- [`<samp>`][samp]: An element for displaying sample output.
- [`<var>`][var]: An element for displaying mathematical variables.
- [`<datalist>`][datalist]: A wrapper for a set of suggested `<option>`s for an `<input>`.
- `<datalist>` is not widely used and is not implemented in Firefox.
- [`<embed type="mimetype" src="url"/>`][embed]:
- An element for generic embedded content.
- `<object>` is generally slightly preferred, but `<img>`, `<audio>`, `<video>`, and the like are preferred over both of them.
- [`<object type="mimetype" data="url">`][object]:
- An element for displaying generic embedded content. Still useful for embedded PDFs etc.
- Generally slightly preferred over `<embed>`, but `<img>`, `<audio>`, `<video>`, and the like are preferred over both of them.
- [`<menu>`][menu]: Officially identical to `<ul>` in syntax and semantics.
- Doesn't have much of a reason to exist.
- [`<progress value=50 max=100>`][progress]: A worse version of `<meter>`.
- Like, this is *exactly* `<meter>`, but without the `min`, `low`, `high`, and `optimum` attributes. Why??
[b]: https://developer.mozilla.org/HTML/Element/b
[strong]: https://developer.mozilla.org/HTML/Element/strong
[i]: https://developer.mozilla.org/HTML/Element/i
[em]: https://developer.mozilla.org/HTML/Element/em
[u]: https://developer.mozilla.org/HTML/Element/u
[s]: https://developer.mozilla.org/HTML/Element/s
[q]: https://developer.mozilla.org/HTML/Element/q
[small]: https://developer.mozilla.org/HTML/Element/small
[sub]: https://developer.mozilla.org/HTML/Element/sub
[sup]: https://developer.mozilla.org/HTML/Element/sup
[code]: https://developer.mozilla.org/HTML/Element/code
[pre]: https://developer.mozilla.org/HTML/Element/pre
[html]: https://developer.mozilla.org/HTML/Element/html
[body]: https://developer.mozilla.org/HTML/Element/body
[heading elements]: https://developer.mozilla.org/HTML/Element/Heading_Elements
[p]: https://developer.mozilla.org/HTML/Element/p
[hr]: https://developer.mozilla.org/HTML/Element/hr
[br]: https://developer.mozilla.org/HTML/Element/br
[wbr]: https://developer.mozilla.org/HTML/Element/wbr
[main]: https://developer.mozilla.org/HTML/Element/main
[section]: https://developer.mozilla.org/HTML/Element/section
[aside]: https://developer.mozilla.org/HTML/Element/aside
[header]: https://developer.mozilla.org/HTML/Element/header
[footer]: https://developer.mozilla.org/HTML/Element/footer
[article]: https://developer.mozilla.org/HTML/Element/article
[nav]: https://developer.mozilla.org/HTML/Element/nav
[div]: https://developer.mozilla.org/HTML/Element/div
[span]: https://developer.mozilla.org/HTML/Element/span
[head]: https://developer.mozilla.org/HTML/Element/head
[title]: https://developer.mozilla.org/HTML/Element/title
[base]: https://developer.mozilla.org/HTML/Element/base
[link]: https://developer.mozilla.org/HTML/Element/link
[meta]: https://developer.mozilla.org/HTML/Element/meta
[style]: https://developer.mozilla.org/HTML/Element/style
[script]: https://developer.mozilla.org/HTML/Element/script
[a]: https://developer.mozilla.org/HTML/Element/a
[img]: https://developer.mozilla.org/HTML/Element/img
[audio]: https://developer.mozilla.org/HTML/Element/audio
[video]: https://developer.mozilla.org/HTML/Element/video
[track]: https://developer.mozilla.org/HTML/Element/track
[canvas]: https://developer.mozilla.org/HTML/Element/canvas
[iframe]: https://developer.mozilla.org/HTML/Element/iframe
[ul]: https://developer.mozilla.org/HTML/Element/ul
[ol]: https://developer.mozilla.org/HTML/Element/ol
[li]: https://developer.mozilla.org/HTML/Element/details
[form]: https://developer.mozilla.org/HTML/Element/form
[button]: https://developer.mozilla.org/HTML/Element/button
[input]: https://developer.mozilla.org/HTML/Element/input
[textarea]: https://developer.mozilla.org/HTML/Element/textarea
[label]: https://developer.mozilla.org/HTML/Element/label
[meter]: https://developer.mozilla.org/HTML/Element/meter
[select]: https://developer.mozilla.org/HTML/Element/select
[option]: https://developer.mozilla.org/HTML/Element/option
[optgroup]: https://developer.mozilla.org/HTML/Element/optgroup
[details]: https://developer.mozilla.org/HTML/Element/details
[summary]: https://developer.mozilla.org/HTML/Element/summary
[map]: https://developer.mozilla.org/HTML/Element/map
[area]: https://developer.mozilla.org/HTML/Element/area
[noscript]: https://developer.mozilla.org/HTML/Element/noscript
[dialog]: https://developer.mozilla.org/HTML/Element/dialog
[marquee]: https://developer.mozilla.org/HTML/Element/marquee
[table]: https://developer.mozilla.org/HTML/Element/table
[thead]: https://developer.mozilla.org/HTML/Element/thead
[tbody]: https://developer.mozilla.org/HTML/Element/tbody
[tfoot]: https://developer.mozilla.org/HTML/Element/tfoot
[tr]: https://developer.mozilla.org/HTML/Element/tr
[td]: https://developer.mozilla.org/HTML/Element/td
[th]: https://developer.mozilla.org/HTML/Element/th
[col]: https://developer.mozilla.org/HTML/Element/col
[colgroup]: https://developer.mozilla.org/HTML/Element/colgroup
[caption]: https://developer.mozilla.org/HTML/Element/caption
[fieldset]: https://developer.mozilla.org/HTML/Element/fieldset
[legend]: https://developer.mozilla.org/HTML/Element/legend
[output]: https://developer.mozilla.org/HTML/Element/output
[figure]: https://developer.mozilla.org/HTML/Element/figure
[figcaption]: https://developer.mozilla.org/HTML/Element/figcaption
[picture]: https://developer.mozilla.org/HTML/Element/picture
[source]: https://developer.mozilla.org/HTML/Element/source
[dl]: https://developer.mozilla.org/HTML/Element/dl
[dt]: https://developer.mozilla.org/HTML/Element/dt
[dd]: https://developer.mozilla.org/HTML/Element/dd
[address]: https://developer.mozilla.org/HTML/Element/address
[blockquote]: https://developer.mozilla.org/HTML/Element/blockquote
[data]: https://developer.mozilla.org/HTML/Element/data
[search]: https://developer.mozilla.org/HTML/Element/search
[time]: https://developer.mozilla.org/HTML/Element/time
[abbr]: https://developer.mozilla.org/HTML/Element/abbr
[cite]: https://developer.mozilla.org/HTML/Element/cite
[del]: https://developer.mozilla.org/HTML/Element/del
[dfn]: https://developer.mozilla.org/HTML/Element/dfn
[ins]: https://developer.mozilla.org/HTML/Element/ins
[kbd]: https://developer.mozilla.org/HTML/Element/kbd
[mark]: https://developer.mozilla.org/HTML/Element/mark
[samp]: https://developer.mozilla.org/HTML/Element/samp
[var]: https://developer.mozilla.org/HTML/Element/var
[datalist]: https://developer.mozilla.org/HTML/Element/datalist
[embed]: https://developer.mozilla.org/HTML/Element/embed
[object]: https://developer.mozilla.org/HTML/Element/object
[menu]: https://developer.mozilla.org/HTML/Element/menu
[progress]: https://developer.mozilla.org/HTML/Element/menu
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