Response Time

Response time is defined as the time between sending a request to a server and the response from the server. This time is also known as a performance and represents an important SEO criterion.

Once a web server receives a request, it is processed immediately. Immediately thereafter, the server will issue a response to the client.

A server response contains the following information: 

  • HTTP version
  • Status code
  • Status text
  • Response date and time

This basic information is called the status line. After the transmission of the status line, the server sends specific header information to the browser. For example, information about the resource, i.e. what kind of content the resource provides, whether it is an HTML document, or a dynamic process, or a session in an online store.

The header will be separated with a blank line from the body in the server response. The response body follows. The actual content is sent and displayed to the user or client. The transfer of the status line, header, and response body should ideally take no more than 1 to 2 seconds. If the requested resource is not found, the user receives an HTTP status code displayed in the form of a short HTML document.


Practical relevance[edit]

The quality of the hardware used, or the infrastructure of the server are important conditions for fast data transfer and a good user experience. If you view a webpage and immediately receive exactly the information that you were looking for, the fast performance of the server will have a positive effect on the user experience. The distance between users and server also plays a role. The closer the server is, the faster the data transfer. However, these effects are only measurable in the range of milliseconds. Nevertheless, the fact still applies, rapid data transfer and continuous availability of the website are prerequisites for satisfied users.

Various server-client models exist. In addition to the above-described standard, where a number of clients are connected to a server, the CDN solution is worth mentioning. A CDN (content delivery network) ensures that performance is excellent even with a large amount of requests and great distance between servers and users. This is achieved by the use of multiple, interconnected servers with different IP addresses. Your request will be answered by the closest server. For high traffic or international websites and online stores, such server solutions are recommended.

Importance of response time for SEO[edit]

The response time of a server is not only important for users so that they can quickly get the information they were looking for. Google does internal studies on this issue. The result: Should a server response take too long; users will spend less time on the website. The length of stay is thus significantly lowered. Moreover, the response time of a server is an important SEO criterion that was included by Google in the algorithms in 2010.