In a denial of service (DoS) attack, an attacker tries to avoid true users from having access to websites or other online services. Unlike other cyberattacks that try to hijack information or make long term damage a DoS attack doesn’t breach security.
A DoS attack works by sending massive amounts of requests to a system in order to overload its capacity and stop it from answering legitimate users.
These types of attacks are usually carried out by hacktivists in order to express their inconformity with the government, politicians, corporations, events, etc.
There is also another type of denial of service attack called distributed denial-of-service (DDoS). In this type of attacks, instead of using a single connection to carry out the attack, the attacker uses multiple connections that are distributed over the internet. This type of attack is much harder to deflect since the volume of request is bigger and comes from many different points.
Flickr photo by Dennis van Zuijlekom https://www.flickr.com/photos/dvanzuijlekom/21470150949 shared under a Creative Commons (BY) license.
Computer and Information Security 