A nice video presentation of what Hadoop is, by Doug Cutting, the father of Hadoop.

http://www.cloudera.com/content/cloudera/en/resources/library/aboutcloudera/beyond-batch-the-evolution-of-the-hadoop-ecosystem-doug-cutting-video.html

Description

Apache Hadoop started as batch: simple, powerful, efficient, scalable, and a shared platform. However, Hadoop is more than that. It’s true strengths are:

• Scalability – it’s affordable due to it being open-source and its use of commodity hardware for reliable distribution.

• Schema on read – you can afford to save everything in raw form.

• Data is better than algorithms – More data and a simple algorithm can be much more meaningful than less data and a complex algorithm.