What is a content delivery network (CDN)?

A content delivery network (CDN) is a group of servers spread across different geographic locations whose job is to deliver web content to users faster. By keeping copies of the content on several servers, a CDN can serve a request from the server that sits closest to the end user.

That cuts the time data needs to travel from the server to the user, which in turn improves the loading speed of the website. CDNs are especially useful for websites with high traffic and global reach, because they reduce latency and take load off the origin server.

Practical examples of CDN use

• Websites with a global audience: for sites that draw visitors from all over the world, a CDN helps deliver content quickly and reliably, no matter where the visitor is.
• Streaming services: streaming platforms such as Netflix or YouTube use CDNs to deliver video efficiently and without buffering.
• E-commerce platforms: online shops use CDNs to load images, product descriptions and other content quickly, which improves the user experience and raises conversion rates.
• Online games: CDNs can cut latency in online games by holding game data closer to the player, which makes for a smoother experience.

Is a CDN important for SEO?

A CDN can have a considerable effect on the search engine optimization of a website. Because search engines such as Google use the loading speed of a page as a ranking factor, speeding up content delivery through a CDN can improve SEO performance. Faster loading times not only improve the user experience, they can also lead to a lower bounce rate and a longer time on page, which in turn sends positive signals to search engines.

How do I use a CDN on my website?

To use a CDN for your website, work through these steps:

1. Pick a CDN provider: choose a provider that fits your requirements. Popular options include Cloudflare, Akamai and Amazon CloudFront.
2. Integration: follow the instructions of your CDN provider to connect your content management system (CMS) or your hosting environment. That usually means changing DNS settings so requests are routed through the CDN.
3. Configuration: adjust the settings of your CDN to define which content should be cached and how often the CDN asks the origin server for fresh versions of that content.
4. Monitoring and tuning: watch how your CDN performs and adjust the configuration when needed to get the most out of it.

Terms that connect to this one are collected in the SEO glossary.

What is clickbait?

Clickbait is a headline that deliberately exaggerates in order to win higher traffic and, with it, higher advertising revenue, by playing on the curiosity of readers. An exciting headline suggests an interesting and revealing article. Once you click through and start reading, the substance is usually thin and unremarkable.

Typical signs of clickbait

Clickbait headlines often lean on call-to-action phrasing, expressions such as “don’t miss this” or “you need to know this”. Other typical signs are superlatives, cliffhangers and strong adjectives or keywords. Topics that are emotionally charged also produce higher click numbers.

Criticism of clickbaiting

Because there is very little informative value behind most clickbait, the method is often criticized, and serious journalists and websites keep moving away from the practices described above.

Despite the fair criticism, clickbait remains an interesting topic in online marketing, because for anyone who depends on high click numbers on their website, clickbaiting is a relatively simple and fast solution. Even so, it is worth keeping in mind that the quality of the website suffers and that critical target audiences are partly put off by it. Some social media platforms such as Facebook already work against it with a changed algorithm, so that clickbait articles are kept out of the news feed.

What are canonical links?

Canonical links, also known as canonicals, are HTML attributes used in the head of a web page to tell search engines which URL is the primary source of a piece of content. They exist to avoid duplicate or near identical content across several pages and to make sure that search engines and visitors are shown the right page.

When should you use canonical links?

A common use case for canonical links is a page that exists in several URL variants, for example with or without www, or on different protocols (HTTP vs. HTTPS). A canonical link names the primary URL, so search engines do not treat the variants as duplicates and only one version gets crawled and shown in the search results.

Another use case is a page that is available on several domain names or subdomains. Here a canonical link states which domain or subdomain is the primary source of the content.

Canonical links can also be used when a page is available for several countries or regions and every region has its own URL. In that case a canonical link states which region is the primary target audience.

What role do canonical links play in online shops?

In online shops, canonical links can play an important part in avoiding duplicate and near identical content and in making sure search engines show shoppers the right product page. Filters and sorting inside a category, for example, can produce several URL variants of one product page. A canonical link states which of them is the primary source of the content.

Canonical links are just as useful when one product is reachable through several category pages or landing pages.

Do canonical links affect SEO?

It is worth keeping in mind that canonical links have no direct effect on your rankings in a search engine, but they do help you avoid trouble with duplicate content and near identical content.

In short: canonical links are HTML attributes in the head of a web page that tell search engines which URL is the primary source of a piece of content. They are used to avoid duplicate or near identical content across several pages and to make sure search engines and visitors land on the right page. Canonical links have no direct effect on rankings, but they do improve usability and the relevance of your content.

Want to know whether the canonicals on your own site point where they should? An SEO audit checks it page by page. taismo also runs a canonical tag generator, currently available in German only. More terms from this field are in the SEO glossary.

What is a cache?

A cache is a temporary storage layer that holds frequently used data so that it can be accessed faster. On a website, a cache keeps elements of a page such as HTML files, CSS stylesheets, JavaScript files and media files, so that they do not have to be loaded from the server again on every single page view.

The benefit of caching lies in shorter loading times and in a lower load on the server, because the files are stored closer to the visitor and can therefore be delivered more quickly.

Which types of cache are there for websites?

1. Browser cache: the web browser stores data of a website on the device of the visitor. When that visitor opens the page again, the browser loads the stored data, which shortens the loading time.
2. Server cache: this type of cache sits on the web server. Frequently requested content is held there so the server can answer requests faster. That lowers the server load and improves response times.
3. Content delivery network (CDN) cache: a CDN distributes copies of website content across servers in different geographic locations. Visitors then receive the content from the server closest to them, which cuts the loading time considerably.
4. Application cache: some web applications use a cache of their own to store data and states temporarily, which is particularly helpful for dynamic applications.

How does caching affect SEO?

Caching plays a substantial role in search engine optimization. A faster loading time gives visitors a better experience, and that is an important factor for search engines like Google, which put a number on it with the Core Web Vitals. Pages that load quickly tend to rank higher in the search results. Effective caching also lowers the bounce rate, because visitors are less likely to leave a page that is there right away.

An efficient cache also lets the web crawlers of search engines work through the content of a website faster and more effectively, which spends the available crawl budget on more pages and improves visibility and indexing. Caching therefore matters not only for the user experience, but also for how visible a website is in search engines.

Whether your caching is set up correctly, and where it still costs you loading time, is one of the points we look at in an SEO audit.