You might think you can never have to much traffic to your website but there are occasions when too much web traffic or traffic overload can significantly and dramatically reduce the performance of your site slowing it down considerably, or even at an extreme level, totally prevent any access to your website completely.
This can be caused quite simply by more people trying to access your website, sending far to many access requests, which are being received by the server(s) than it or they can handle, hopefully due to the sites popularity, but may be due to a premeditated, maliciously orchestrated, intentional attack on the site but lets err on the more optimistic side and assume it is simply caused by over-popularity. Larger companies or organisations that have the infrastructure to host large scale websites with several servers can usually deal with such large unanticipated anomalies in unforeseen traffic overload or significant increase in volumes and it is more likely that smaller services are affected by sudden and unexpected traffic overload.
Unexpected and unanticipated popularity
An unanticipated and unexpected rise in publicity may unintentionally cause you to experience web traffic overload.
An newly instigated email campaign, or a backlink from a popular site you have information published on, reference to a news item you may have referred to that the search engines seize up on, are some of the incidents that may cause such an increase in visitors (sometimes called the Digg, Reddit or Slashdot effect) that overwhelm your site.
You may have experienced your self websites that have been required to shutdown after an unforeseen massive increase in traffic. This is for the most part those website run by individuals renting their bandwidth from ISP or hosting companies. Having said that, there have been occasions where some sites backed by mush larger companies operating with their own servers who have also been caught out by the inconvenience of over popularity.
A good example of this was when, the Vision of Britain Through Time site, which containing information taken from the 1901 UK census, was advertised on numerous TV programmes it causing such a stir of interest that the site had to be taken down until alternative arrangements were made to allow the site to cope with the extreme volumes of new traffic.
Denial of Service (DoS) attacks
By far, a more malicious way of creating traffic overload at a website is the Denial-of-service attacks (DoS attacks) have forces a website to closedown after an intentional and sustained attack which floods a site with far more requests than it was initially designed to cope with.