Downtime in IT is when a piece of equipment (such as a computer or other device) is not functioning or can’t function in the way it was designed. Downtime is a subjective concept and can be easily defined as being the opposite of uptime. Usually, we use the term “downtime” to refer to periods when a system, device, computer or internet website is unavailable.

Internet website downtime means that the end-user cannot:

  • access the website,
  • perform and complete the main task on the website

Nowadays, downtime is more complex than we believed even a few years ago. Website downtime (opposite to website uptime) is when a website is unavailable online or can’t function well enough for end-users to complete the main task. For example, the primary user task in e-commerce is to add to the basket and buy products or services. Another example from the accommodation/hotel industry is that users can choose and book a room. When the user can’t perform these tasks on the website (even if the user can access the website) it is referred to as downtime.

Common reasons a website might be down are:

  • human error – e.g. wrong DNS entry on the server, error in PHP causing disconnection with database, any other error caused by people
  • equipment failure – e.g. server or network breakdown, power outage and any other reason caused by the hardware
  • malicious attack – e.g. malware infection, Distributed Denial-of-Service (DDoS) attack, DNS (Domain Name Servers) cache poisoning, hijacking or redirection, any other malicious activity causing website downtime
  • catastrophic accident and natural disaster – e.g. fire in the server room (read about this in our article “Fire in the server room – why do you need independent backup“)
  • traffic overload – it is funny that success can be a failure; if you expect massive traffic, first check that your server can deal with it. 

Each downtime creates costs (loss) for the website owner,  read more about it in our article “Cost of website downtime” (article published on