Here are a few of the rel attributes you all discovered in this week’s assignment.
REL='subresource'
The rel=subresource link is what is called Link prefetching, where the browser tries to fetch the resource before it’s needed, so it can load that resource faster from cache when it is in fact needed later on. (More)
REL='Chrome-Webstore-Item'
Creates a link to a website/service’s app installer in the Chrome Web Store. This allows users to install related apps or extensions for Google Chrome directly from the website, without the need to be redirected to the Chrome Web Store.
rel='apple-touch-icon-
When browsing the web with an Apple mobile device, users have the option of saving web pages directly to their home screen. When a page is saved, this icon is generated to which users may use to access the webpage. Precomposed Apple touch icons are rendered with rounded corners, but without a gloss effect.
REL='alternate'
A link to a version of the current document, especially for the specified device or medium indicated by the media attribute.
REL='shortlink'
The shortlink relationship allows webmasters to specify a short link to use for the resource, thereby avoiding having to obtain one from a potentially unreliable third party URL shortening service such as tinyurl.com.
REL='nofollow'
rel = “nofollow” is a relationship attribute that is assigned to a hyperlink to inform search engines and bots not to follow links with this attribute. Nofollow also tells the search engine that by clicking a link with this attribute should not influence the ranking in the search engine’s index. The effectiveness of this attribute is to improve that quality of search engine results and to prevent spamming from occurring. For instance a link to a form that uses nofollow would not allow search engine robots to sign in or register on your site.
- http://en.wikipedia.org/wiki/Nofollow
- http://support.google.com/webmasters/bin/answer.py?hl=en&answer=96569
- http://microformats.org/wiki/rel-nofollow
REL='canonical'
A canonical page is the preferred version of a set of pages with highly similar content
Use canonical URLs to improve link and ranking signals for content available through multiple structures or via syndication
It’s common for a site to have several pages listing the same set of products. For example, one page might display products sorted in alphabetical order, while other pages display the same products listed by price or by rating. For example:
If Google knows that these pages have the same content, we may index only one version for our search results. Our algorithms select the page we think best answers the user’s query. Now, however, users can specify a canonical page to search engines by adding a <link> element with the attribute rel=”canonical” to the <head> section of the non-canonical version of the page. Adding this link and attribute lets site owners identify sets of identical content and suggest to Google: “Of all these pages with identical content, this page is the most useful. Please prioritize it in search results.”
REL='shortcut icon'
Loads in a Favicon for the page.
REL='pingback'
Pingbacks (also known as trackbacks) are a form of automated comment for a page or post, created when another WordPress blog links to that page or post.
When you publish a new blog post, WordPress attempts to ‘ping‘ all the sites that were linked to in your post. i.e. Your WordPress website is informing other websites that you’ve linked to them.
When you receive pingpacks, then it means someone else has linked to one of your posts or pages. (:source^) (also learn more: WordPress.com Support, Wikipedia, and the Codex glossary)
REL='dns-prefetch'
DNS resolution time varies from <1ms for locally cached results, to hundreds of milliseconds due to the cascading nature of DNS. This can contribute significantly towards total page load time. This filter reduces DNS lookup time by providing hints to the browser at the beginning of the HTML, which allows the browser to pre-resolve DNS for resources on the page. –https://developers.google.com/
REL='external nofollow'
Nofollow is a co-ordinated efforts from Google, yahoo , MSN to stop crawling links that are considered not trustworthy or spammy. Today many blogs, message boards, forums, news sites use nofollow tag to prevent spam in their comments or other areas of the blogs or forums. Now there is a new tag that is similar to rel=nofollow that is rel=external nofollow, external nofollow works the same as nofollow tag but this tag opens links in a new window instead of the same window. If you want to try just add rel=”external” it will open the link in a new window. It sort of works like target=_blank.
rel="manifest"
The web app manifest provides information about an application (such as name, author, icon, and description) in a text file. The purpose of the manifest is to install web applications to the homescreen of a device, providing users with quicker access and a richer experience.
Web app manifests are part of a collection of web technologies called progressive web apps, which are web applications that can be installed to the homescreen of a device without needing the user to go through an app store, along with other superpowers such as being available offline and presenting users with push notifications when application content changes.