Technical Description:
A distributed denial of service (DDoS) occurs when a server is overwhelmed and cannot provide services due to all of the large number of client computers coming from different locations.
Real World Example:
One example of a similar situation involves holiday shopping; specifically, the day after American Thanksgiving known as Black Friday. On this day, people leaves their different homes to go shopping at local stores. For this scenario, we will imagine that the people are all going to the same store. Due to the crowd, there may be many people waiting outside the store.
Geekinese Translation:
Both situations have similar ideas. Many different sources arriving at the same destination at roughly the same time. On the technical side, the server is unable to respond the all of the client computers. From the real world example, the store is unable to handle all of the shoppers. In both scenarios, the result is same. The destination is overwhelmed.