What is a hyperlink?

Generally speaking, these are not ne­ces­sar­ily linear texts that are linked to other texts via hy­per­links. The term 'hy­per­tex­t' was coined by American philo­soph­er Ted Nelson. The most wide­spread hypertext system in the world is the world wide web (also known as 'web' or 'www'). On the web, hy­per­links are im­ple­men­ted using the markup language HTML to link web pages and other resources together. In this article, we con­cen­trate on hy­per­links in web documents and present their structure, prop­er­ties, and give some examples of their use.

In HTML documents, hy­per­links are im­ple­men­ted using <a> and <link> elements. While the <a> element defines the position of a hyperlink in the content area (body) of an HTML document, the element <link> in the header area (head) is used to define re­la­tion­ships with other documents and resources.

In the following paragraph, we con­cen­trate on the <a> element, in other words on hy­per­links in the HTML body. They are visible to website visitors, can be clicked on, and belong to the central nav­ig­a­tion tools of the world wide web, just as the address bar in the browser or the input fields of search engines.

Hy­per­links in the HTML body are im­ple­men­ted using the anchor element a. The basic schema cor­res­ponds to the following example:

The a element consists of a start and an end tag, which are enclosed in angle brackets, and are typical for HTML. The start and end tags of the a element surround the so-called link text. A visible and clickable text element.

Al­tern­at­ively, you can also store image elements with hy­per­links. In this case, the start and end tag of the a elements surround the HTML code in order to embed the graphic.

As a rule, element a not only defines the anchor of the hyperlink and the starting point for the link but also the link target. The hyperlink’s target is specified by the attribute href, which has a unique iden­ti­fi­er – the Uniform Resource Iden­ti­fi­er (URI) – as a value. The target of a hyperlink is usually the URL of a web resource or a page jump to another part of the document. HTML at­trib­utes and their values are defined sep­ar­ately by blank spaces in the start tag of the re­spect­ive HTML element.

The link examples above both lead to a website that has https://www.example.org as its URL. This is possible thanks to HTTPS. By default, this type of hyperlink directs internet users to the top of the linked website.

However, if it is a link to an internal target in the current document, an HTML markup would be used according to the following scheme:

Note that link targets within a document must be defined as markers from HTML5 onwards using unique IDs. In HTML4, the attribute name was used in the a element.

If, on the other hand, you want to link to a page jump in an external document, you can combine the URL of the target page with a hash (#) and the re­spect­ive ID of the desired page jump.

Element a has no mandatory elements in principle. If a hyperlink is to be im­ple­men­ted, the link target must be specified via href. In addition, the a element supports various at­trib­utes that can be im­ple­men­ted if required in order to provide ad­di­tion­al in­form­a­tion for users or user agents.

The following table contains the most relevant at­trib­utes of the a element:

Hy­per­links with different functions are used to link web pages. Different types of links have been es­tab­lished by internet users and now seen as common. These can be roughly divided into internal and external hy­per­links. Internal links are all links between a domain’s in­di­vidu­al subpages. External links connect different domains to each other. Internal and external links are used primarily by human users to navigate websites. An ad­di­tion­al benefit of hy­per­links in the context of search engine op­tim­isa­tion (in short: SEO) only emerged with the creation of Google bots, es­pe­cially search engine crawlers that also use hy­per­links to develop websites and evaluate con­nec­tions to other websites. For a long time, hy­per­links were the main criteria for a website’s rating, a fact that made them decisive for search engine rankings. Today, the im­port­ance of the hyperlink has become re­lativ­ised. Modern search engine al­gorithms use a multitude of ranking factors to present internet users with the most relevant results for each search query. Nev­er­the­less, the internal linking and backlink profile are still very important for search engine op­tim­isa­tion.

Internal hy­per­links

The or­gan­isa­tion of internal links within a web project is called the link structure. Link struc­tures are based on strategic ob­ser­va­tions. The aim is to direct the flow of visitors through the website in an orderly fashion. This is referred to as click paths.

Click paths usually have a specific purpose, for example, web store operators want to sell goods and services, attract sub­scribers to the news­let­ter or encourage visitors to par­ti­cip­ate in a sweepstake.

Possible struc­tures for internal linking are the linear structure, the tree structure, the star structure, and the network structure:

• Linear structure: within a linear link structure, subpages of a web page are linked in such a way that a pre­defined click path is created. Visitors always access websites with a linear link structure in the order desired by the operator, which gives them maximum control over the click path. However, visitors may find this structure somewhat confining. The linear link structure is typical for dynamic web projects such as blogs

• Tree structure: if the internal linking follows a tree structure, the website is based on a structure in which subpages of the project are assigned to different hierarchy levels. Link struc­tures like these are typical for web stores. The visitor usually accesses a landing page first that has been optimised for the search engine and then clicks their way through to the desired category and product pages. The thematic ori­ent­a­tion of the web pages (category, sub­cat­egory, product, article) is usually more specific the further the potential customer gets into the website

• Star structure: a star structure is when a webpage offers several links to other similar webpages within the same project. Or­gan­isa­tion­al prin­ciples like these are typical for online en­cyc­lo­pae­di­as such as Wikipedia. In each article, users will find hy­per­links to other relevant articles in which the linked items are explained in more detail

• Network structure: network-shaped struc­tures are char­ac­ter­ised by the fact that almost all subpages of a web project are linked on every web page. A website visitor has the pos­sib­il­ity of reaching the desired subpage of the website from any point

Keep in mind that the link struc­tures presented here are abstract. As a rule, website operators use a mixture of internal links that combine the link strategies of these presented concepts. For example, a website can basically follow the tree structure and at the same time offer a network link structure via nav­ig­a­tion menus, sidebars, and footers that enables potential customers to leave the current click path and switch to another category, product, or service page.

Internal hy­per­links are of central im­port­ance to a website’s usability. A web project with a good link structure offers users short click paths to the desired content and en­cour­ages them to discover other parts of the website. Good internal linking con­trib­utes to increased retention time i.e. visitors staying longer on the website. SEO experts also regard user-friendly internal linking as one of the central factors for good search engine ranking.

External hy­per­links

The group of external hy­per­links includes all links from one website to another. Every link between two domains is – depending on how you see it – either an outbound or an incoming hyperlink.

Outbound hy­per­links

Outbound hy­per­links are hy­per­links on your own website that link to another domain’s web resource. As a rule, external links are used as ref­er­ences or re­com­mend­a­tions for further content.

Note that external hy­per­links lead internet users away from your website and to another one. With every external link comes the risk of losing visitors. This can be com­pensated for using the HTML attribute target. If you implement external links according to the following scheme, the link target of the external link will open in a new tab or window, depending on the browser settings. Your website will remain open in the browser and the visitor won’t lose sight of it.

A dis­ad­vant­age of the target attribute is that website visitors cannot decide for them­selves where the link should be opened. If target="_blank" is used, you should always use the attribute rel with the value noopener for security reasons:

Whether a website contains outbound links or not has no direct positive influence on the search engine ranking. This was revealed by Google employee, John Mueller in May 2016 in a Google Web­mas­ters hangout session on YouTube. However, according to Mueller, hy­per­links that offer added value to the visitor by linking to high-quality and trust­worthy content increase the quality of the website. Therefore, you should not com­pletely refrain from using outbound hy­per­links. Although Google denies that outbound links have a direct, positive influence, it is un­doubt­able that outbound hy­per­links can have a negative influence on the ranking of a website. If a website has too many unnatural outbound links, there is a danger that search engines will classify them as spam and will penalise the website.

As a website operator, you should exercise caution when using external hy­per­links since linking to other websites could have legal con­sequences, for example, copyright in­fringe­ment or hy­per­links leading to illegal gambling content.

If you want to prevent an outbound link on your website from being con­sidered a re­com­mend­a­tion by the search engine, you can instruct the crawler to ignore the link in question. To do this, use the attribute rel with the value nofollow. Nofollow links are not con­sidered relevant by search engine al­gorithms. This type of link has es­tab­lished itself as the standard, es­pe­cially for web projects where visitors can also publish their own content including hy­per­links. Online forums, rating platforms, online magazines, and Wikis protect them­selves from spam this way. This spam serves solely to build links within the framework of Black Hat SEO.   

Incoming hy­per­links

Incoming hy­per­links (also called inbound links or backlinks) are all links that lead from other domains to your own web project. All the incoming links together form a website’s backlink profile. The links in your backlink profile can be roughly divided into two cat­egor­ies, depending on the target link:

• Surface links
• Deep links

Surface links are links to the homepage or different landing pages of your web project. Deep links, on the other hand, are backlinks that lead to a specific subpage of your website. Deep links can also target media content on your website such as videos, images, or documents offered for download (i.e. PDFs). These are also referred to as media links. Backlinks can also be dif­fer­en­ti­ated from one another in terms of their link source. Search engine op­tim­isa­tion dis­tin­guishes between content links, sidebar links, and footer links as well as comment links and social signals.

• Content links: content links are links that lead from the text content of another website to your domain. Content links can be either deep or surface links. Hy­per­links like this usually represent a re­com­mend­a­tion regarding the contents of your website. Search engine providers also interpret content links as being of strong quality and of relevance. Content links are par­tic­u­larly valuable when it comes to search engine op­tim­isa­tion. When eval­u­at­ing a content link, the search engine takes factors into account such as the link text, the thematic ori­ent­a­tion of the linked website, and how trust­worthy the link source is.

• Sidebar and footer links: sidebar and footer links have something in common. They are not directly im­ple­men­ted in a web page’s text. They are found in parts of the menu at the side or the end of the page. In the blogger scene, for example, it is common practice to link to friends or topic-relevant blogs in the sidebar. This is known as a blogroll. Footer links are sometimes used on corporate websites to link business partners, customers, industry as­so­ci­ations, press com­ment­ar­ies, or sponsors. Since sidebar and footer links used to be used primarily for unnatural link building measures, these types of hy­per­links are of minor im­port­ance when assessing a website’s relevance. However, if a backlink profile contains lots of unnatural sidebar and footer links, this can lead to the search engine provider auto­mat­ic­ally or manually de­valu­at­ing the website

• Comment links: comment links are hy­per­links in user-generated text content such as blog comments, reviews, or articles in online forums. Many website operators offer visitors the op­por­tun­ity to comment on content or rate products and services. In some cases, hy­per­links to other websites can also be placed in the re­spect­ive posts, which, like all other inbound links, appear in the backlink profile of the linked website. Like sidebar and footer links, comment links can be ma­nip­u­lated and it’s easy to create an unnatural backlink profile. In order to prevent spam, hy­per­links in comments are often im­ple­men­ted auto­mat­ic­ally as nofollow links

• Social signals: in Web 2.0, users have become ac­cus­tomed to sharing content that they like, think is dis­cus­sion-worthy, or want to promote with their contacts on social media platforms. These are also hy­per­links that link to the re­spect­ive website from the social network. These are referred to as social signals. Whether or how search engine al­gorithms rely on social signals such as likes, shares, and comments to evaluate the relevance of a website is quite con­tro­ver­sial – es­pe­cially since network operators only grant limited access to social media content to search engine crawlers such as the Google bot

A natural backlink profile usually contains each of the link types listed above. High-quality, topic-relevant content links are decisive for the search engine ranking. Nev­er­the­less, every natural inbound link is a good link, as it allows internet users to visit your website and rep­res­ents a potential traffic source. Social signals in par­tic­u­lar offer great potential to reach new groups of visitors, es­pe­cially when shared content goes viral.