how does google work

Book on Amazon: http://amzn.to/2mpc2pT How does Google work? The world wide web is currently made up of 60 trillion individual pages and is constantly growing. So how is it that Google can search all of these pages in less than a second and find exactly what you want? script How does Google work? The world wide web is currently made up of 60 trillion individual pages and is constantly growing. So how is it that Google can search all of these pages in less than a second and find exactly what you want? Well interestingly, Google doesn't actually search the web. When you type a search term into Google, it actually searches its own internal database, known as the Index. The Index is like a giant filing cabinet that contains a summary sheet for each of the trillions of web pages. To create the Index Google has programs, called Spiders, that constantly crawl around the web, and record information about web pages, like; key words, hyperlinks and content quality. So when you press search in Google, it searches the Index, and then returns links to the web pages that it thinks are most appropriate. Although the index is considerably smaller than the internet it still contains over 100 million gigabytes of information, so returning fast search results still requires a giant infrastructure of data centres and servers. Google's infrastructure is so powerful that it can handle 100,000 servers all simultaneously exchanging data at 10 gigabytes per second. That's enough processing power to read the scanned contents of the library of Congress, which takes up 838 miles of bookshelves, in just one tenth of a second! But it’s not just the hardware that makes Google so fast. All of its algorithms are specially designed to be quick and efficient, even when thousands of people are using them at the same time. Which is quite important, given that Google gets around 40,000 search queries every second. That's around a football stadium full of people using Google every second! So how does Google find what you want? The search algorithm that Google uses to sort web pages is constantly evolving. When Google was founded in 1998 its algorithm primarily relied on two key factors to rank web pages: The number of key words on a page, and the number of inbound hyperlinks. However, since then the algorithm has been modified thousands and thousands of times, and it now uses over 200 factors to rank web pages, including things like: Domain name, page layout, usability, reading level, loading speed, etc. To test algorithm modifications Google constantly run hundreds of experiments. In every experiment a small fraction of users, around 1%, are exposed to a modified version of the algorithm. This might be a small modification like, modifying the weighting of a key factor, or it could be a large change, like completely re-coding the algorithm. If the modified version improves user experience or gives better search results, then it is incorporated into the search engine. Google come up with so many algorithm modifications that there simply isn't enough time for them to test each one independently. Instead, they make multiple changes to the algorithm at the same time, and then use statistical analysis to determine which modifications improve search results. This means that every time you type a search query into Google you will be taking part in, not one, but multiple different experiments at the same time. In fact, Google have run so many experiments, that it is estimated that over 1,000 man years of work has gone into the development of its search algorithm. And that's why Google is so good at finding what you want. Thanks for watching. And if you found this interesting, and would like to read a book about the amazing story behind Google, then click on the link in the description below.