Today's Google Doodle explained: Who is George Boole - and what does the doodle actually mean?

The English mathematician laid the foundations for today’s search engines

Googlers pose at a building site in the Netherlands, where the company is building a huge new data centre — much of which will be powered by the work of George Boole (VINCENT JANNINK/AFP/Getty Images)

Google is celebrating the 200th anniversary of George Boole’s birth with a special Google Doodle.

The English mathematician’s work is especially close to Google’s heart, since his discoveries are central to powering the search box that sits beneath the little animation.

The Google Doodle highlights some of Boole’s most important work — Boolean logic, and Boolean operators. Boole died in 1864, but his work was key to the search engines that power much of the internet today.

The Boolean operators seen in the Doodle are a way to understand how the different parts of a search relate to one another. They include common words like AND, but also strange ones like XOR.

Each of the different operators tells a search engine how it should deal with a query that is made up of more than one word.

AND, for instance, tells a search engine that it should look for anything that has both words in it. OR tells it that should look for anything that has one of the words in it. And XOR is an exclusive OR — meaning that it should only look for things that have one or the other word in them, rather than either.

The basic functions of Boolean operators can be seen in the little animation that makes up the Google. The second, lowercase G shows which of x and y would be generated by each of the different operators, and it cycles through to show the full functions of each one. It also shows how they can be each be combined: a search for “x AND y” and “x OR y” would bring up both letters, for instance.

The different operators were once central to the working of search engines including Google, but also those that powered libraries and other important stores of information. They have gradually dropped away from being obvious, but the logic underpinning them still powers the way we think about search engines.

Google has gradually folded the operators’ functions into its normal search, meaning that the search engine can guess how the words connect to each other without using the commands. That’s largely because people are so used to heading to Google and putting in what they’re looking for that it doesn’t make sense any more.

If you’re searching for “Xbox or PlayStation”, for instance, it’s more likely that you’re looking for information about which of the two consoles are best, rather than pages that include one or the other word.

Google’s Advanced Search page now allows for many of the same searches, but explained in a slightly more obvious way. So you can get the function of the OR operator by typing in the “any of these words” box, for instance, or the NOT operator by using the “none of these words” field.

Boolean operators were just one of the many discoveries that Boole made. But many of them were in a similar field — exploring logic and the way it works to create rules so that different parts of thought can be more neatly arranged.