A malicious attack attempting to disrupt normal traffic of an internet-connected service or system, such as a website, or online shop, by flooding the target with ‘traffic’.
Such traffic can look like legitimate attempts to access the target system but, actually leverage a network of compromised computers and other internet-connected devices to generate the malicious traffic.
Such networks are referred to as Botnets.
In simple terms, a DDoS attack is analogous to a huge number of vehicles hitting a motorway simultaneously, causing congestion and preventing the flow of traffic altogether.
This renders the target of the attack ‘unreachable’ and therefore ‘denies service’ to regular users.