HTML, XML

<?xml version="1.0"?>
<response value="ok" xml:lang="en">
  <text>Ok</text>
  <comment html_allowed="true"/>
  <ns1:description><![CDATA[
  CDATA is <not> magical.
  ]]></ns1:description>
  <a></a>
</response>
<!DOCTYPE html>
<title>Title</title>
<style>body {width: 500px;}</style>
<script type="application/javascript">
  function $init() {return true;}
</script>
<body>
  <p checked class="title" id='title'>Title</p>
  <!-- here goes the rest of the page -->
</body>

CSS

@media screen and (-webkit-min-device-pixel-ratio: 0) {
  body:first-of-type pre::after {
    content: 'highlight: ' attr(class);
  }
  body {
    background: linear-gradient(45deg, blue, red);
  }
}
@import url('print.css');
@page:right {
 margin: 1cm 2cm 1.3cm 4cm;
}
@font-face {
  font-family: Chunkfive; src: url('Chunkfive.otf');
}
div.text,
#content,
li[lang=ru] {
  font: Tahoma, Chunkfive, sans-serif;
  background: url('hatch.png') /* wtf? */;  color: #F0F0F0 !important;
  width: 100%;
}

LESS

/*
Using the most minimal language subset to ensure we
have enough relevance hints for proper Less detection
*/
@import "fruits";
@rhythm: 1.5em;
@media screen and (min-resolution: 2dppx) {
    body {font-size: 125%}
}
section > .foo + #bar:hover [href*="less"] {
    margin:     @rhythm 0 0 @rhythm;
    padding:    calc(5% + 20px);
    background: #f00ba7 url(http://placehold.alpha-centauri/42.png) no-repeat;
    background-image: linear-gradient(-135deg, wheat, fuchsia) !important ;
    background-blend-mode: multiply;
}
@font-face {
    font-family: /* ? */ 'Omega';
    src: url('../fonts/omega-webfont.woff?v=2.0.2');
}
.icon-baz::before {
    display:     inline-block;
    font-family: "Omega", Alpha, sans-serif;
    content:     "\f085";
    color:       rgba(98, 76 /* or 54 */, 231, .75);
}

SCSS

@import "compass/reset";
// variables
$colorGreen: #008000;
$colorGreenDark: darken($colorGreen, 10);
@mixin container {
    max-width: 980px;
}
// mixins with parameters
@mixin button($color:green) {
    @if ($color == green) {
        background-color: #008000;
    }
    @else if ($color == red) {
        background-color: #B22222;
    }
}
button {
    @include button(red);
}
// nested definitions
ul {
    width: 100%;
    padding: {
        left: 5px; right: 5px;
    }
  li {
      float: left; margin-right: 10px;
      .home {
          background: url('http://placehold.it/20') scroll no-repeat 0 0;
    }
  }
}
.banner {
    @extend .container;
}
a {
  color: $colorGreen;
  &:hover { color: $colorGreenDark; }
  &:visited { color: #c458cb; }
}
@for $i from 1 through 5 {
    .span#{$i} {
        width: 20px*$i;
    }
}
@mixin mobile {
  @media screen and (max-width : 600px) {
    @content;
  }
}

Apache

# rewrite`s rules for wordpress pretty url
LoadModule rewrite_module  modules/mod_rewrite.so
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . index.php [NC,L]
ExpiresActive On
ExpiresByType application/x-javascript  "access plus 1 days"
Order Deny,Allow
Allow from All
<Location /maps/>
  RewriteMap map txt:map.txt
  RewriteMap lower int:tolower
  RewriteCond %{REQUEST_URI} ^/([^/.]+)\.html$ [NC]
  RewriteCond ${map:${lower:%1}|NOT_FOUND} !NOT_FOUND
  RewriteRule .? /index.php?q=${map:${lower:%1}} [NC,L]
</Location>

Ini

;Settings relating to the location and loading of the database
[Database]
ProfileDir=.
ShowProfileMgr=smart
Profile1_Name[] = "\|/_-=MegaDestoyer=-_\|/"
DefaultProfile=True
AutoCreate = no
[AutoExec]
use-prompt="prompt"
Glob=autoexec_*.ini
AskAboutIgnoredPlugins=0

PHP

require_once 'Zend/Uri/Http.php';
namespace Location\Web;
interface Factory
{
    static function _factory();
}
abstract class URI extends BaseURI implements Factory
{
    abstract function test();
    public static $st1 = 1;
    const ME = "Yo";
    var $list = NULL;
    private $var;
    /**
     * Returns a URI
     *
     * @return URI
     */
    static public function _factory($stats = array(), $uri = 'http')
    {
        echo __METHOD__;
        $uri = explode(':', $uri, 0b10);
        $schemeSpecific = isset($uri[1]) ? $uri[1] : '';
        $desc = 'Multi
line description';
        // Security check
        if (!ctype_alnum($scheme)) {
            throw new Zend_Uri_Exception('Illegal scheme');
        }
        $this->var = 0 - self::$st;
        $this->list = list(Array("1"=> 2, 2=>self::ME, 3 => \Location\Web\URI::class));
        return [
            'uri'   => $uri,
            'value' => null,
        ];
    }
}
echo URI::ME . URI::$st1;
__halt_compiler () ; datahere
datahere
datahere */
datahere

Python

@requires_authorization
def somefunc(param1='', param2=0):
    r'''A docstring'''
    if param1 > param2: # interesting
        print 'Gre\'ater'
    return (param2 - param1 + 1 + 0b10l) or None
class SomeClass:
    pass
>>> message = '''interpreter
... prompt'''

Markdown

# hello world
you can write text [with links](http://example.com) inline or [link references][1].
* one _thing_ has *em*phasis
* two __things__ are **bold**
[1]: http://example.com
---
---
hello world
===========
<this_is inline="xml"></this_is>
> markdown is so cool
    so are code segments
1. one thing (yeah!)
2. two thing `i can write code`, and `more` wipee!

JSON

[
  {
    "title": "apples",
    "count": [12000, 20000],
    "description": {"text": "...", "sensitive": false}
  },
  {
    "title": "oranges",
    "count": [17500, null],
    "description": {"text": "...", "sensitive": false}
  }
]

Javascript

import {x, y} as p from 'point';
const ANSWER = 42;
class Car extends Vehicle {
  constructor(speed, cost) {
    super(speed);
    var c = Symbol('cost');
    this[c] = cost;
    this.intro = `This is a car runs at
      ${speed}.`;
  }
}
for (let num of [1, 2, 3]) {
  console.log(num + 0b111110111);
}
function $initHighlight(block, flags) {
  try {
    if (block.className.search(/\bno\-highlight\b/) != -1)
      return processBlock(block.function, true, 0x0F) + ' class=""';
  } catch (e) {
    /* handle exception */
    var e4x =
        <div>Example
            <p>1234</p></div>;
  }
  for (var i = 0 / 2; i < classes.length; i++) { // "0 / 2" should not be parsed as regexp
    if (checkCondition(classes[i]) === undefined)
      return /\d+[\s/]/g;
  }
  console.log(Array.every(classes, Boolean));
}
export  $initHighlight;

Coffeescript

grade = (student, period=(if b? then 7 else 6), messages={"A": "Excellent"}) ->
  if student.excellentWork
    "A+"
  else if student.okayStuff
    if student.triedHard then "B" else "B-"
  else
    "C"
square = (x) -> x * x
two = -> 2
math =
  root:   Math.sqrt
  square: square
  cube:   (x) -> x * square x
race = (winner, runners...) ->
  print winner, runners
class Animal extends Being
  constructor: (@name) ->
  move: (meters) ->
    alert @name + " moved #{meters}m."
hi = `function() {
  return [document.title, "Hello JavaScript"].join(": ");
}`
heredoc = """
CoffeeScript subst test #{ 010 + 0xf / 0b10 + "nested string #{ /\n/ }"}
"""
###
CoffeeScript Compiler v1.2.0
Released under the MIT License
###
OPERATOR = /// ^ (
?: [-=]>             # function
) ///