by Dinesh Thakur Category: DIGITAL CONCEPTS

This was first created by an English mathematician named George Boole in 1847 and yet, in one of the strange quirks of the computer industry, is now used in everything from circuit design to searching the Internet. In essence Boole developed a system for reducing complex questions into simple yes or no answers by using what are known as truth tables, sometimes called gates.

Although these truth tables or gates can take several forms the three that are relevant to Internet searches are AND, OR and NOT. Each one operates differently.


This produces an output only if two specified conditions are met. For example if a search was made on the words 'Economic' AND 'Policy' the truth table would be as follows:

1st Condition            2nd Condition               Output

(Economic)           (Policy)

NO                            NO                                           NO

YES                          NO                                           NO

NO                            YES                                         NO

YES                          YES                                         YES

Only if both words were found on the same website would a match be returned.


This produces an output if either specified condition is met. In the same example as above the truth table would be:

1st Condition        2nd Condition                  Output

(Economic)           (Policy)

NO                              NO                                            NO

YES                            NO                                            YES

NO                              YES                                          YES

YES                            YES                                           YES

If either word is found on a website a match would be returned.


This returns an output only if a specified condition is not met. To continue the above example if a search was made on the words 'Economic' NOT 'Policy' the truth table would be:

1st Condition             2nd Condition               Output

(Economic)                (Policy)

YES                                  YES                                       NO

NO                                    YES                                       NO

YES                                   NO                                        YES

NO                                     NO                                        NO

Only websites which contain the word 'Economic' but do not contain the word 'Policy' will be returned.

In electronics the output from one set of gates can become the input to others to produce complex switching arrangements which forms the basis of the computer microchip itself. Away from that it is by combining these various logical operators (as AND, OR and NOT are known) that highly precise Internet searches can be conducted, as will soon become clear.

About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.C.A, MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.