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.