228 lines
10 KiB
Markdown
228 lines
10 KiB
Markdown
[HTML5 Boilerplate homepage](https://html5boilerplate.com) | [Documentation
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table of contents](TOC.md)
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# The HTML
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By default, HTML5 Boilerplate provides two `html` pages:
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* [`index.html`](#indexhtml) - a default HTML skeleton that should form the
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basis of all pages on your website
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* [`404.html`](#404html) - a placeholder 404 error page
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## `index.html`
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### The `no-js` class
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The `no-js` class is provided in order to allow you to more easily and
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explicitly add custom styles based on whether JavaScript is disabled
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(`.no-js`) or enabled (`.js`). Using this technique also helps [avoid the
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FOUC](https://www.paulirish.com/2009/avoiding-the-fouc-v3/).
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## Language attribute
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Please consider specifying the language of your content by adding the `lang`
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attribute to `<html>` as in this example:
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```html
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<html class="no-js" lang="en">
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```
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### The order of the `<title>` and `<meta>` tags
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The order in which the `<title>` and the `<meta>` tags are specified is
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important because:
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1) the charset declaration (`<meta charset="utf-8">`):
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* must be included completely within the [first 1024 bytes of the
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document](https://www.whatwg.org/specs/web-apps/current-work/multipage/semantics.html#charset)
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* should be specified as early as possible (before any content that could
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be controlled by an attacker, such as a `<title>` element) in order to
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avoid a potential [encoding-related security
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issue](https://code.google.com/p/doctype-mirror/wiki/ArticleUtf7) in
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Internet Explorer
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2) the meta tag for compatibility mode
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(`<meta http-equiv="x-ua-compatible" content="ie=edge">`):
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* [needs to be included before all other tags except for the `<title>` and
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the other `<meta>`
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tags](https://msdn.microsoft.com/en-us/library/cc288325.aspx)
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### `x-ua-compatible`
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Internet Explorer 8/9/10 support [document compatibility
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modes](https://msdn.microsoft.com/en-us/library/cc288325.aspx) that affect the
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way webpages are interpreted and displayed. Because of this, even if your site's
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visitor is using, let's say, Internet Explorer 9, it's possible that IE will not
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use the latest rendering engine, and instead, decide to render your page using
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the Internet Explorer 5.5 rendering engine.
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Specifying the `x-ua-compatible` meta tag:
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```html
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<meta http-equiv="x-ua-compatible" content="ie=edge">
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```
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or sending the page with the following HTTP response header
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```
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X-UA-Compatible: IE=edge
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```
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will force Internet Explorer 8/9/10 to render the webpage in the highest
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available mode in [the various cases when it may
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not](https://hsivonen.fi/doctype/#ie8), and therefore, ensure that anyone
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browsing your site is treated to the best possible user experience that
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browser can offer.
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If possible, we recommend that you remove the `meta` tag and send only the
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HTTP response header as the `meta` tag will not always work if your site is
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served on a non-standard port, as Internet Explorer's preference option
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`Display intranet sites in Compatibility View` is checked by default.
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If you are using Apache as your webserver, including the
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[`.htaccess`](https://github.com/h5bp/server-configs-apache) file takes care of
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the HTTP header. If you are using a different server, check out our [other
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server config](https://github.com/h5bp/server-configs).
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Starting with Internet Explorer 11, [document modes are
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deprecated](https://msdn.microsoft.com/en-us/library/ie/bg182625.aspx#docmode).
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If your business still relies on older web apps and services that were
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designed for older versions of Internet Explorer, you might want to consider
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enabling [Enterprise Mode](http://blogs.msdn.com/b/ie/archive/2014/04/02/stay-up-to-date-with-enterprise-mode-for-internet-explorer-11.aspx) throughout your company.
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## Mobile viewport
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There are a few different options that you can use with the [`viewport` meta
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tag](https://docs.google.com/present/view?id=dkx3qtm_22dxsrgcf4 "Viewport and
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Media Queries - The Complete Idiot's Guide"). You can find out more in [the
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Apple developer docs](https://developer.apple.com/library/safari/documentation/AppleApplications/Reference/SafariWebContent/UsingtheViewport/UsingtheViewport.html).
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HTML5 Boilerplate comes with a simple setup that strikes a good balance for general use cases.
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```html
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<meta name="viewport" content="width=device-width, initial-scale=1">
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```
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## Favicons and Touch Icon
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The shortcut icons should be put in the root directory of your site. HTML5
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Boilerplate comes with a default set of icons (include favicon and one Apple
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Touch Icon) that you can use as a baseline to create your own.
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Please refer to the more detailed description in the [Extend section](extend.md)
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of these docs.
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## Modernizr
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HTML5 Boilerplate uses a custom build of Modernizr.
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[Modernizr](http://modernizr.com) is a JavaScript library which adds classes to
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the `html` element based on the results of feature test and which ensures that
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all browsers can make use of HTML5 elements (as it includes the HTML5 Shiv).
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This allows you to target parts of your CSS and JavaScript based on the
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features supported by a browser.
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In general, in order to keep page load times to a minimum, it's best to call
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any JavaScript at the end of the page because if a script is slow to load
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from an external server it may cause the whole page to hang. That said, the
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Modernizr script *needs* to run *before* the browser begins rendering the page,
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so that browsers lacking support for some of the new HTML5 elements are able to
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handle them properly. Therefore the Modernizr script is the only JavaScript
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file synchronously loaded at the top of the document.
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## What about polyfills?
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If you need to include [polyfills](https://remysharp.com/2010/10/08/what-is-a-polyfill)
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in your project, you must make sure those load before any other JavaScript. If you're
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using some polyfill CDN service, like [cdn.polyfill.io](https://cdn.polyfill.io/),
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just put it before the other scripts in the bottom of the page:
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```html
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<script src="https://cdn.polyfill.io/v1/polyfill.min.js"></script>
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<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js"></script>
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<script>window.jQuery || document.write('<script src="js/vendor/jquery-1.11.2.min.js"><\/script>')</script>
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<script src="js/plugins.js"></script>
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<script src="js/main.js"></script>
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</body>
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```
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If you like to just include the polyfills yourself, you could include them in
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`js/plugins.js`. When you have a bunch of polyfills to load in, you could
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also create a `polyfills.js` file in the `js/vendor` directory. Also using
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this technique, make sure the polyfills are all loaded before any other
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Javascript.
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There are some misconceptions about Modernizr and polyfills. It's important
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to understand that Modernizr just handles feature checking, not polyfilling
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itself. The only thing Modernizr does regarding polyfills is that the team
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maintains [a huge list of cross Browser polyfills](https://github.com/Modernizr/Modernizr/wiki/HTML5-Cross-Browser-Polyfills).
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## The content area
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The central part of the boilerplate template is pretty much empty. This is
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intentional, in order to make the boilerplate suitable for both web page and
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web app development.
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### Browser Upgrade Prompt
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The main content area of the boilerplate includes a prompt to install an up to
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date browser for users of IE 6/7. If you intended to support IE 6/7, then you
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should remove the snippet of code.
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### jQuery CDN for jQuery
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The jQuery CDN version of the jQuery JavaScript library is referenced towards
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the bottom of the page. A local fallback of jQuery is included for rare instances
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when the CDN version might not be available, and to facilitate offline
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development.
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The jQuery CDN version was chosen over other potential candidates
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([like Google's Hosted Libraries](https://developers.google.com/speed/libraries/))
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because it's fast ([comparable or faster than Google by some
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measures](https://www.cdnperf.com/#jsdelivr,cdnjs,google,yandex,microsoft,jquery,bootstrapcdn/https/90))
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and, (unlike Google's CDN) is available to China's hundreds of millions of internet users.
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For many years we [chose](https://github.com/h5bp/html5-boilerplate/issues/1191)
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the Google Hosted version over the jQuery CDN because it was available
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over HTTPS (the jQuery CDN was not,) and it offered a better chance of
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hitting the cache lottery owing to the popularity of the Google CDN.
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The first issue is no longer valid and the second is far outweighed by
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being able to serve jQuery to Chinese users.
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While the jQuery CDN is a strong default solution your site or application may
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require a different configuration. Testing your site with services like
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[WebPageTest](https://www.webpagetest.org/) and browser tools like
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[PageSpeed Insights](https://developers.google.com/speed/pagespeed/insights/) or
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[YSlow](https://developer.yahoo.com/yslow/) will help you examine the real
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world performance of your site and can show where you can optimize your specific
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site or application.
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### Google Universal Analytics Tracking Code
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Finally, an optimized version of the Google Universal Analytics tracking code is
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included. Google recommends that this script be placed at the top of the page.
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Factors to consider: if you place this script at the top of the page, you’ll
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be able to count users who don’t fully load the page, and you’ll incur the max
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number of simultaneous connections of the browser.
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Further information:
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* [Optimizing the Google Universal Analytics
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Snippet](https://mathiasbynens.be/notes/async-analytics-snippet#universal-analytics)
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* [Introduction to
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Analytics.js](https://developers.google.com/analytics/devguides/collection/analyticsjs/)
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* [Google Analytics Demos & Tools](https://ga-dev-tools.appspot.com/)
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**N.B.** The Google Universal Analytics snippet is included by default mainly
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because Google Analytics is [currently one of the most popular tracking
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solutions](https://trends.builtwith.com/analytics/Google-Analytics) out there.
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However, its usage isn't set in stone, and you SHOULD consider exploring the
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[alternatives](https://en.wikipedia.org/wiki/List_of_web_analytics_software)
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and use whatever suits your needs best!
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