Learn the key ideas of the book by Neel Mehta , Aditya Agashe , Parth Detroja

Swipe to Unlock

The inner workings of today’s technology

How does Spotify choose which songs to suggest to its users? What factors influence the Facebook algorithm? Why does Amazon change its prices every ten minutes? At one time or another, we have all wondered how these things work, but you don’t have to be a tech expert to find the answers. In Swipe to Unlock, three product managers at Google, Facebook and Microsoft answer some of the most frequently asked questions, and analyse real cases to illustrate the mechanisms that regulate the technology that has become part of our daily lives.

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How any Google search works: from keyword density to the Page Rank algorithm

Whenever you search for something on Google, the search engine goes through more than 30 trillion web pages, and, in just half a second, it finds the top 10 results that answer your question. How is this possible? Google doesn't actually visit every page on the Internet each time you ask a question, but it stores information about web pages in its databases, and uses algorithms that read those databases to decide what to show you.

These databases are built through programs called spiders, which continuously scan the web’s pages. Google is constantly adding new pages to its database, or updating pages as they change. When you perform a search, Google takes your query - the text you typed in the search bar - and scans its database to find the most relevant web pages.

To do this, Google uses an algorithm called PageRank, which Google founders Larry Page and Sergey Brin created for their PhD thesis in 1998. Page and Brin noted that a webpage's importance can be estimated by looking at what other important pages link to it. Thus, through algebraic calculations, PageRank assigns each web page a score based on the PageRank scores of every other page that refers to it, scores which depend on the pages that link to these pages, and so on.

Once Google has found all the pages in its index that mention your search query, it then ranks them using PageRank and other criteria, such as the location from which the query was made, or how recently a web page has been updated, and ignores websites that appear to be spam. However, remember that Google's search algorithm is constantly evolving, with minor updates being launched over 500 times a year.


The key ideas of "Swipe to Unlock"

How any Google search works: from keyword density to the Page Rank algorithm
How does Spotify pick songs and Netflix pick films for each user? Using collaborative filtering
The key factors that influence Facebook’s algorithm: interaction with the creator of a post, other people’s interest in that same post, the type of post and how recent it is
A Mac computer is more difficult to hack than a PC, but is not immune to viruses
Why most are apps available for free download: the freemium economy
How does Facebook earn billions without charging its users a cent?
The documents we archive in the “cloud” are not actually in a cloud, but in massive buildings known as data centres
How Amazon monetises through user data and why they change their prices every 10 minutes
The strengthening of their international presence, data use, domination of the world’s photos and mobile data: why Facebook bought Whatsapp
When a messaging app is an operating system: how WeChat became the “official” app in China
Take-home message
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