Boolean operators are a limited set of words that can be used in search queries to narrow results. They are useful to know when you want to find specific results within search engines, especially when using popular keywords and phrases. Google may find millions of results for some queries, so using Boolean operators helps you find the most relevant results.
The most common Boolean operators are AND, OR, and NOT. Using these basic operators, you can choose to include or exclude certain words, whether on their own or in conjunction with other words.
Use in computer science
Boolean operators are very commonly used in computer science, particularly in database administration. Popular database query languages like SQL are composed primarily of Boolean operators to access and modify data in a database.
For example, a basic search query in SQL looks like:
SELECT firstname FROM customers WHERE gender='male' AND age='21'
This query would search a database of customer data to find only customers that are both male and 21 years old. If the AND were changed to OR, then it would find customers who are either male or 21 years old (or both). Doing this, and adding more specific terms, helps you to quickly locate the records you are after, even in databases with millions of entries.
Search engines like Google also use Boolean operators in a very similar fashion. By using Boolean operators in search queries, it helps them understand your search intention and find you the most relevant results.
For example, Boolean operators can also be used to exclude certain information in order to narrow results. In the case of search engines, NOT is usually represented by a minus sign (-). So, the search term 'Restaurants -Italian' would search for restaurants, but exclude any that mention they are Italian.
Which Boolean operators can be used for queries in search engines?
There are a number of different Boolean operators that can be used with Google and other search engines in queries. Boolean operators are not always necessary with modern search engines, as Google uses a lot of external information to help provide context and understand search intent.
Boolean operators are particularly useful when you have either very wide or very narrow search queries. When information is hard to find because there is either too much of it or too little, Boolean operators can help be more specific, so that Google can find you the most relevant results.
AND and OR are the most common Boolean operators in search queries. Between them, you can specify that multiple search terms must either exist or not exist together. So for example, you could find Chinese restaurants by searching 'restaurants AND Chinese'. If you also wanted Indian food, you could search for 'restaurants AND Chinese OR Indian' to search for both cuisines at once. You can wrap terms in brackets () when you need clarity, such as 'restaurants AND (Chinese OR Indian)'.
However, most search engines like Google are smart enough nowadays that using boolean operators with basic keywords is of almost trivial use. Instead, they are much better used with search phrases. These are quotes or search terms composed of multiple words, which must exist together.
Wrapping search terms in double quotes("") specifies that an exact phrase must be found. This is particularly useful when searching for academic articles and journals, where specific information can be very difficult to find, and using single keywords is not enough.
At the same time, information can be excluded by using the minus sign(-). This is equivalent to the Boolean operator NOT. It can be used in conjunction with other Boolean operators, including searching for exact phrases. Adding a minus sign in front of an exact phrase can exclude specific search phrases from results, which can sometimes be just as useful at finding the most relevant information.
The tilde character (~) also works on Google and results in including synonyms of the term in the results. So, using the keyword '~soda' would return results for soda and also for ‘fizzy drink’, ‘soft drink’, ‘carbonated beverage’, and other synonyms. This is particularly useful in cases where either there is not a definitive name for what you want, or there are regional variations and you want to easily find results for all of them.
The asterisk character (*) works as a wildcard in Google searches. These are used for when you want all possible permutations of a word or phrase. So, for example, a search for 'wom*n' would return results for both woman and women. Or, a search for 'work*' would search for work, working, worked, etc.
Boolean operators are very useful when combined and can help Google find you the most relevant results. Despite all the contextual information available to them, there is still plenty of room for ambiguity depending on the terms and phrases used. Being aware of the different Boolean operators and knowing how to use them can help you provide the extra information needed to find the best results from potentially millions of options.