# Search Engine Optimization (SEO)
A helpful checklist / collection of Search Engine Optimization (SEO) tips and technics.

## Table of Contents
* [URL](#url)
* [Meta Information](#meta-information)
* [Keywords](#keywords)
* [Content](#content)
* [Images](#images)
* [Links](#links)
* [Social Media](#social-media)
* [Sitemap](#sitemap)
* [Errors and access](#errors-and-access)
* [Performance](#performance)
* [UX](#ux)
* [Mobile](#mobile)
* [Validation and accessibility](#Validation-and-accessibility)
* [Search](#search)
* [Analytics](#analytics)
* [Tools](#tools)

## URL
* **Descriptive URLs:** use a descriptive page url, which should reflect your targeted keyword
* **Subdomain or subfolder:** subdomains are seen as separate domains
* **Hyphans:** split words using hyphans
* **[www or no-www](https://support.google.com/webmasters/answer/44231):** provide both domains, but set a prefered version in Google Webmaster Tools
* **[Localisation](https://support.google.com/webmasters/answer/62399):** chookse a country-specific domain, for better local search results
* **[HTTPS](http://googlewebmastercentral.blogspot.be/2014/08/https-as-ranking-signal.html):** Security is a top priority for Google
* **[URL builder](https://support.google.com/analytics/answer/1033867):** Use this tool to add custom compaign parameters to your URLs

## Meta Information
* **Title:** each page shound have a unique speaking title (60 - 100 characters)  
`<title>Website Title</title>`
* **Description:** each page should have a unique description (max. 160 characters)  
`<meta name="description" content="">`

## Keywords
* **Single:** every page shound have a single unique targeted keyword
* **Research:** rank for keywords with high traffic and less competition
* **URL:** keyword should appear in URL name
* **Title:** keyword should appear in page title
* **Heading:** keyword should appear in headings
* **Content:** keyword should apear in ~3% of article length
* **[Meta Tag](https://www.youtube.com/watch?v=jK7IPbnmvVU):** you can ommit the `<meta name="keywords" content="">`, search engines do not use this meta tag

## Content
* **Content:** Content matters the most in SEO
* **Headings:** Clear structure `H1` -` H6` max. 70 characters long
* **Strong:** use `strong` tag to highlight your targeted keyword
* **Uniqueness:** do not provide duplicated content, use unique content types
* **Length:** article should be at least 300 words
* **Freshness:** new content is important. Updating pages or regulary posting is recommended

## Images
* **File name:** use a short descriptive name
* **Alt tag:** add an alt-tag this a description of the image (60 - 70 characters)
* **Dimentions:** add the `width=""` and `height=""` attributes to the image
* **[Responsive Images](http://www.w3.org/TR/html-picture-element/):** serve the most optimized image corresponding to the window size
* **Size:** keep the filesize as low as possible
* **[Optimization](https://imageoptim.com/):** Optimize images by removing some meta information

## Links
* **Title:** add a descriptive title to links
* **Backlinks:** Only add external links if you got a backlink to your site
* **nofollow:** add `rel="nofollow"` attribute to external links
* **Internal links:** add ~3 internal links to your content

## Social Media
* **Social Shares:** provide sharing options for your site
* **[Social Profiles]((https://developers.google.com/webmasters/structured-data/customize/social-profiles)):** add social profiles to your Google search results
* **[OpenGraph](http://ogp.me/):** The Open Graph protocol enables any web page to become a rich object in a social graph.
* **[Facebook](https://developers.facebook.com/docs/sharing/best-practices):** Sharing Best Practices for Websites & Mobile Apps
* **[Twitter](https://dev.twitter.com/cards/getting-started):** with Twitter cards, you can attach photos, videos and media experience to you Tweets
* Authorship information
* **[Google+ Authorship](https://www.youtube.com/watch?v=FgFb6Y-UJUI):** add Google+ authorship information to your page  
`<link rel="author" href="https://plus.google.com/u/0/[GOOGLE+ ID]">`  or  
`<a href="https://plus.google.com/u/0/[GOOGLE+ ID]" rel=author">Google+ Profile</a>` or  
`<a href="https://plus.google.com/u/0/[GOOGLE+ ID]" rel=me">Google+ Profile</a>` or  
`<a href="https://plus.google.com/u/0/[GOOGLE+ ID]" rel=publisher">Google+ Profile</a>`

## Sitemap
* **HTML sitemap:** An HTML sitemap allows site visitors to easily navigate a website.
* **[XML sitemap](https://support.google.com/webmasters/answer/183668):** Help search engines to index your pages
* **[Image sitemap](https://support.google.com/webmasters/answer/178636):** Increase that your images can be found in Image Search results
* **[Video sitemap](https://support.google.com/webmasters/answer/80471):** Make sure, search engines know about all the video content on your site
* **[Mobile sitemap](https://support.google.com/webmasters/answer/6082207):** For feature phones, you can create a mobile sitemap

## Errors and access
* provide 403 - Acced denied page
* provide 404 - Page not found page
* add a `robots.txt` file
* Avoid `FILE_NOT_FOUND` errors

## Performance
* Performance and loading time matters
* only serve concatenated and minified files
* if possible no redirects
* compress images ([ImageOptim](https://imageoptim.com/))

## UX
* User friendly site
* clickable links should not be too small

## Mobile
* add viewport tag

```
 <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1.0">
 ```

* create a mobile-friendly site ([shown in search results](http://googlewebmastercentral.blogspot.be/2014/11/helping-users-find-mobile-friendly-pages.html))
* [Mobile-Friendly Test](https://www.google.com/webmasters/tools/mobile-friendly/)
* [AppLinks](http://applinks.org/documentation/)

## Validation and accessibility
* Write valid markup ([HTML Validator](http://validator.w3.org/) [CSS Validator](http://jigsaw.w3.org/css-validator/))
* use [WAI-Aria](http://www.w3.org/TR/wai-aria/) tags
* use [RichSnippets](http://schema.org/)

## Search
* [Provide a custom search](https://developers.google.com/custom-search/) ([schema.org/SearchAction](http://schema.org/SearchAction), [RichSnippet](https://developers.google.com/webmasters/richsnippets/sitelinkssearch?utm_source=wmc-blog&utm_medium=direct-referral&utm_campaign=sitelinks-searchbox))

## Analytics
* [Google Analytics](http://www.google.com/analytics/)
* [Piwik](http://piwik.org/)
* [Yahoo Web Analytics]( (web.analytics.yahoo.com))

## Tools
* [Google Webmasters](https://www.google.com/webmasters/)
* [Bing Webmasters](http://www.bing.com/toolbox/webmaster)
* [PageSpeed Insights](https://developers.google.com/speed/pagespeed/insights/)
* [AdWords Keyword Tool](https://adwords.google.com/KeywordPlanner)
* [Google Trends](http://www.google.com/trends/)
* [Structured Data Testing Tool](http://www.google.com/webmasters/tools/richsnippets)
* [Structured Data Testing Tool](https://developers.google.com/structured-data/testing-tool/)
* [Google+ Snippet Creator](https://developers.google.com/+/web/snippet/)
* [seo tool by feedthebot](http://www.feedthebot.com/tools/)
* [Twitter card validator](https://cards-dev.twitter.com/validator)
* [Facebook Debugger](https://developers.facebook.com/tools/debug)