Hyperlink.

The hyperlink is the founding principle of the World Wide Web. Tim Berners-Lee designed it for exactly this purpose at CERN in Geneva in 1989: documents were to be connected by references, so that you could jump from one to the next. The term hypertext had already been coined by Ted Nelson in the 1960s. Technically, a link in HTML is an a element with an href attribute that specifies the destination, and a visible text, the anchor text.

A distinction is made between internal links, which stay within the same website, and external links to other websites. There are also jump links within a page, links to files such as PDFs and links with special protocols: mailto: opens the email program, tel: dials a number directly on a phone. On the mobile websites of tradespeople and service providers in particular, the tel: link is often the most important link of all.

For search engines, links are both signposts and recommendations. Through internal links, Google finds a website's subpages and recognises which of them are important. External links from other websites, known as backlinks, count as a trust signal. In both cases the anchor text matters: 'More on web design in Zurich' tells a search engine far more than 'click here'.

For visitors, one simple rule applies: a link must be recognisable as a link and deliver what its text promises. If a link leads nowhere, a 404 error results, which costs trust. Broken links can be found regularly with a crawl of the website. An example: a painting firm links from its text about facade renovation to the page on costs, using the anchor text 'cost of a facade renovation' instead of 'click here'. Visitors know what to expect, and Google understands the connection. The state of an existing website's internal links is shown by a website audit; they are maintained on an ongoing basis in ongoing SEO.