What Is Hadoop?
Hadoop is a very clever software designed to help with the above situation. As we said, we may have 5 billion users click on the record. We want to analyze these data to create suggestions for people; so they can find the product they want faster and buy more! How do we do this? We have already said that it is too big (and the server is faster).
So Hadoop comes in, basically says: buy a lot of business hardware (basically, cheap desktop, you can get from anyone) and connect them together. One of these desktops (or nodes) will be the brain of this thing. When you give it the data, it will automatically store it on one of the nodes. When you need to query, you send a query to the brain, and the brain asks each desktop to return any results that are being stored.
What Is Big Data?
Big data is just an idea that the amount of data we generate (more important is the collection) is growing rapidly. More importantly, the company is realizing that these data can be used to make more accurate predictions, so make them earn more money. For example, Facebook knows how often you have access to many sites (due to the popularity of the Facebook button) and would like to use this information to show you ads that are more likely to click
For More Details-Hadoop Course Details