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4.3 How does Boolean relate to searching the Internet? 

So, as suggested in the previous section, 'Boolean logic' can be used to create precise searches using a search engine. In fact, it is relevant to any search you carry out on a search engine ...

For example, let's say you want to find something about ships and you use the following terms ..

ship vessel trawler boat

the search engine will actually default to a Boolean interpretation of your query, even if this is not made explicit. In other words, it will assume something like:

ship AND vessel AND trawler AND boat (ie. find me a page that contains all these terms)

or, alternatively, depending on how it is programmed, it may assume:

ship OR vessel OR trawler OR boat (ie. find me a page that contains any of these terms)

You may prefer it to be 'OR' (ie. find a page containing any of the terms) rather than AND (ie. must contain all the terms) and so you can specify this using Boolean operators as shown above. 

There is another way, however, of specifying a complex search, rather than typing in your query in Boolean (with 'OR', 'AND','NOT etc). Many search engines offer an Advanced Search page which, in effect, creates a complex Boolean query for you, but by using user-friendly menus.

The Google Advanced Search page, pictured below, is a good example ... 'with all of the words' is a user-friendly way of telling you the search engine will put a Boolean AND between each word, whereas 'any of the words' is equivalent to OR between each word and 'without the words' equivalent to using NOT.  

Note other useful features ... in particular, the ability to specify domains (eg. 'only return results from the site or domain .uk' would limit results to British sites which have the .uk ending).

Advanced Search may be the best option if you do not feel confident with writing your own Boolean query from scratch.

[nb. for a detailed guide to Boolean, see the following site 
http://library.albany.edu/internet/boolean.html]