Become Better At Finding Stuff With Search Engines: Boolean Search Logic Explained

Google Search Logo   Become Better At Finding Stuff With Search Engines: Boolean Search Logic ExplainedThe number of websites currently in existence is unimaginable. And while – on a bad day – it only takes Google’s thousands of servers half a second to query approximately 50 billion indexed pages, it takes you significantly longer to scan only the first page of search results. On top of that, you are likely to digress and open irrelevant sites. Why don’t you do your constantly distracted and easily overwhelmed brain a huge favor and learn how to properly construct a search?

Boolean search logic illustrated in Venn diagrams can help you visualize what you are searching for. If you think this sounds suspiciously like mathematics, you’re spot on. But don’t let that discourage you! It’s pure and simple logic, demonstrated with pretty and very simple diagrams, and so it’s easy. I promise! And I have fun examples to prove it.

The only case in which you won’t need any search logic, is when you search for only a single word, like Earth.

Venn Diagram Earth   Become Better At Finding Stuff With Search Engines: Boolean Search Logic Explained

What Is Boolean (Search) Logic?

In a search query, Boolean logic helps us define the logical relationship between multiple search terms. The operators used to express the relationship are AND, OR, and NOT. Any number of boolean search terms can be connected with these operators to refine your search results. Let’s look at each operator separately.

OR

  • search results will contain either one or several or all of the search terms
  • best used when you want to pull together results on similar topics

Example: Wind OR Fire

Boolean Search Logic OR   Become Better At Finding Stuff With Search Engines: Boolean Search Logic Explained

The Venn diagram above reveals that a search for Wind OR Fire will show results for Wind, Wind AND Fire (overlapping areas), and Fire.

Example: Earth OR Wind OR Fire

Boolean Search Logic OR 3   Become Better At Finding Stuff With Search Engines: Boolean Search Logic Explained

Likewise, this diagram demonstrates that all boolean search terms by themselves, as well as overlapping content will be shown when connecting the terms with OR. And here is a chance to earn a Like including 5 bonus points if you can tell me who those folks in the center are.

Here are the numbers for Google’s search results for the three search terms and the OR combinations shown above:

  • Earth: 1,280,000,000 results
  • Wind: 909,000,000 results
  • Fire: 2,090,000,000 results
  • Wind OR Fire: 2,980,000,000 results
  • Earth OR Wind OR Fire: 4,210,000,000

As you see, in the case of a Google search, the whole is not greater than the sum of its parts; it’s actually smaller. But since there is redundancy, i.e. overlapping areas, as can be seen nicely in the Venn diagrams above, that makes sense.

Instead of OR you can also use the vertical bar | character when performing a Google search.

NOT or rather -

  • exclude keywords from your search
  • best used when your search is ambiguous

Caution: While NOT is a valid term in Boolean logic, Google doesn’t appear to operate with this term. Instead of NOT, you should use the - character. Note that there is no space between the dash and the keyword you want to exclude.

Example: Wind NOT Fire or Wind -Fire

Boolean NOT   Become Better At Finding Stuff With Search Engines: Boolean Search Logic Explained

The Venn diagram above depicts the results in theory. Below are the actual numbers:

  • Wind: 909,000,000 results
  • Fire: 2,090,000,000 results
  • Wind NOT Fire: 377,000,000 results
  • Wind -Fire: 1,810,000,000
  • and just for fun… Fire -Wind: 5,010,000,000 results

The numbers will vary, depending on which Google domain you are using (my browser defaults to Google.ca) and obviously they also change over time. However, the results above are nothing short of confusing. Let’s say that Google doesn’t necessarily give us all the results, so those numbers are not a reliable source of information. Looking at the first page of results, however, can give you an idea of whether or not your search worked.

Google Search Results Compared   Become Better At Finding Stuff With Search Engines: Boolean Search Logic Explained

Actually trying to understand the results quickly reveals that Google tends to think for you, rather than with you. For the majority of users that’s good because they don’t know what they are doing. Google appears to serve results based on its “experience” rather than the search terms and operators used in the query. This actually is a little disturbing, but good to be aware of. So let’s continue with the theory…

AND

  • search results will contain all search terms
  • results where one of the terms is missing will be excluded
  • best used when you want to retrieve only those results where the search terms overlap

Example: Earth AND Wind AND Fire

Boolean Search Logic AND   Become Better At Finding Stuff With Search Engines: Boolean Search Logic Explained

Once more, the numbers:

  • Earth: 1,280,000,000 results
  • Wind: 909,000,000 results
  • Fire: 2,090,000,000 results
  • Earth AND Wind AND Fire: 80,500,000
  • and just for fun… Earth Wind Fire: 86,800,000

At least Google cooperates with this boolean search operator. Mind you that AND typically is the default operator in search engines. So whenever you type in more than one keyword, the search engine will automatically connect them with the AND operator. Hence Earth Wind Fire in theory will yield the same search results as Earth AND Wind AND Fire.

Processing & Nesting

You can connect multiple search terms with different operators. But since Boolean logic operates based on mathematical principles, the order in which you connect your keywords will have an effect on your results. To influence your results, it helps to understand how the terms are processed. Per default, keywords are processed from left to right.

Example: Earth AND Wind OR Fire

Boolean Search Logic AND OR   Become Better At Finding Stuff With Search Engines: Boolean Search Logic Explained

If you want to change the order in which your keywords are processed, you can of course literally change the order. You can also enclose a set of search terms and operators in parentheses, i.e. nest them. Processing will still be left to right, but the nested elements will be treated as one unit.

Example: Earth AND (Wind OR Fire)

Boolean Search Logic AND OR Nested   Become Better At Finding Stuff With Search Engines: Boolean Search Logic Explained

This result looks quite different, doesn’t it?

Conclusion

It’s generally good to know how Boolean search logic works when you are working with search engines, at least if they strictly adhere to those operators. Apparently, Google does not, meaning a simple search will often get you exactly what you need, without having to think about it. If you do want to be sure that Google does what you want it to do however, use Google’s Advanced Search. The field all these words corresponds to the AND operator, any of these words equals OR, and none of these words works like NOT. Now you should be able to narrow down your searches a lot better – in theory.

If you desire to become a real power user, I recommend reviewing our article on how to master Google search operators, or how to reduce irrelevant results, or which tricks to use when you don’t know what to search for , or simply review Google’s list of search operators.

Have you ever had trouble getting Google or another search engine find what you were looking for?

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52 Comments -

null

Oh no, it’s mathematics.

Bert Teuling

The Bunch in the middle are Earth Wind and Fire A wonderful fusion funk group that were before their time:)

Keith S

And let us NOT leave out… I CAN’T REMEMBER THEIR NAME! Oh, well, It is late & I am sleepy! Later bro & YES: Earth Wind and Fire were before their time:) :)

Lavender

No, they weren’t. They were of their time. Just because their music is better than what’s called music now, doesn’t mean they were before their time.

Dee Martin

Loved this – I will share – great way to teach kids how to narrow search results! (And I love Earth, Wind and Fire – Keep Your Head to the Sky!

Scott M

I have been doing it this this for a while now after being tipped by a friend.I hat to say it about a monolith but they have a search engine that rises far above all of the others,excepting specific tech search engines.

Jason Heiken

It’s Earth Wind and Fire. And, I didn’t even need to look it up. (yup….I’m that old…)

Anup Agarwal

The bunch in the middle are funky American band. The members are Maurice White, Philip Bailey, Al McKay, Verdine White, Larry Dunn, Ronnie Laws, Sonny Emory, Ralph Johnson, Don Myrick, Kim Johnson, Roland Bautista, Wade Flemons, Jessica Cleaves, Daniel de los Reyes, Andrew Woolfolk, Philip Bailey Jr, Gary Bias, Myron Mckinley, Bobby Burns Jr., B. David Whitworth, Raymond Lee Brown, Greg “G-Mo” Moore, Morris O’ Connor, Sheldon Reynolds, John Paris, Fred White, Reggie Young

Lavender

*Gasp!* And yet you’re on a computer? And using the Internet?! Shades of Jethro Gibbs! Who knew people over 35 could walk and chew gum, let alone use a computer! (Besides me, that is. Since I’ve been on the Internet since 1994. And yep, I’M that old, too!)

null

LOL! But good info….Shared.

Steve Fahnestalk

Well, duh–it’s the group Earth, Wind and Fire. A great group for its day.

Your Mom

You’re an ass

Steve Fahnestalk

*I’m* an ass? You’re the dipsh*t casually insulting people you don’t know for no reason.
Or, as Captain Kirk said, “Double dumbass on you!”

Your Mom

ha ha – quoting Captain Kirk – your mom was right.
the ‘well, duh’ comment was lame and insulting to a girl that did a pretty good job in her post. You got the 5 points, but sorry you lost 3 for being a tool.

Steve Fahnestalk

“Duh,” is well-known as shorthand for “That’s an obvious question,” and is only seen as insulting by idiots. Which you obviously are.
If the person who wrote the article has a problem–and she’s probably a woman, not a girl, you sexist pig–then she can take it up with me herself.
You, on the other hand, are too young and stupid to waste any more time on. I’m done with you. Post away, dumbass!

Mrs. Steve

Stop responding to your mom that way – she’s only trying to provoke you

Steve Fahnestalk

You’re right. But she’s hardly old enough to be *my* mom, who–by the way–had a degree and knew the difference between “who” and “that” as well as “girl” and “woman.”

But, you know, I’d hate to see the species die out entirely–if we don’t feed the trolls, who will we laugh at when they die of hunger?

Mrs. Steve

That’s the way these Obama lovers are. Always critical of the rest of us. That person probably has no job and has the government paying for her high-speed internet, how else is she casually responding to posts during the workday?

Lavender

(The *Gasp!* comment was for Jason Heiken. Apparently some old folks can’t hit the correct reply button).

Greg Moyer

Earth wind and fire

null

I am always trying new ways to get better search results. This will help

Guy McDowell

It’s the Jackson 5 with 4 cousins.

I just don’t find that Google responds as strictly to Boolean operators as it once did. I barely even bother with them anymore. Which is sad.

Tina Sieber

Yeah, that’s what I found. I guess Google developed their algorithm to adapt to people’s logic rather than to teach people how to properly use search operators.

Monali Parmar

I use Boolean logic every single day at work! I am a Sourcing Analyst in the Recruiting world and most of us use this to find qualified candidates by zeroing in on certain keywords. I will also use this in my personal life if I need to narrow down my Google results while shopping or just doing research. Thanks for sharing this!

Brian

The folks in the middle…are the singing group: Earth, Wind, and Fire (I had their hit “September” going through my mind when I first saw your post).

Mark Soderlund

Dear null – It isn’t mathematics – it’s Logic.

Earth Wind and Fire – good band – excellent stage show – especially if you catch them on the 21st of September.

Ralph John Soden

Love it! Nice way to show logic meaning.

null

This posting helped me find a song. Thank you Tina.

Tina Sieber

Very welcome!

Ali Khan

A great info to share …. interesting :))

Ben

In the diagram, the fourth picture down, the picture in the center is a depiction of all three – Earth, Wind, and Fire.

dr anwar yarkhan

Excellent writeup. Thanks.
Request one go PDF file instead of giving so many reference links. And without frills please. Great topic greater insight.

Tina Sieber

I’m not sure I understand your suggestion. Would you like to have a PDF of the article or a PDF with references or a PDF with both?

dr anwar yarkhan

Search Engines. There are several writeups explaining how to use se. Like: how to master Google search operators; how to reduce irrelevant results; tricks to use when you don’t know what to search for; and others to educate to deal with se., may kindly be given in single writeup in PDF format. Thanks.

Tina Sieber

Ah, you’re asking for a PDF manual on the subject. We do have a search manual already, but it doesn’t go into the theory that much.

Cynthia Nevin

The group is Earth, Wind and Fire!

Rochelle

The people are Earth, Wind and Fire, a rock group.

Russ

Great article that is clear and easy to understand.

Tina Sieber

Glad to hear that, Russ. :)

Vincent Paul Migliore

The people in the center are the singing group, “Earth, Wind and Fire” !! Cool, huh? (Which true of WIND (maybe), but not EARTH -OR- FIRE.

isse

“Google tends to think for you, rather than with you … This actually is a little disturbing”

Over time, I’ve become too disturbed by Google to use them any longer. Does this advice apply apply similarly to Bing?

I already use quotes and the minus sign, but I’d never heard of using the vertical bar, parenthesis or that keyword order changed the processing..

Tina Sieber

I didn’t try Bing. However, if you use the examples above and compare the numbers, you should be able to figure out how strictly Bing adheres to operators or how much the search results are controlled by custom algorithms.

Chip Stewart

The folks in the middle are Earth, Wind & Fire, a band from, like, the late 60s, man. They are some of the coolest, hippest musicians around!

KRS

I think PROXIMITY SEARCH is the most important search engine feature after word or string finding — that is, limiting results to hits in which one term or string appears within X number of words from the other. As a lawyer,I use Lexis/Nexis and WestLaw proximity operators constantly, along with the invaluable KWIC (Key Word In Context) view, to eliminate innumerable false hits where the two words (or strings) are scattered.

Google has the NEAR operator, and Exaled has a more useful version, but I’d switch in a heartbeat to a search engine with Lexis/Nexis or WestLaw proximity operators and KWIC. In fact, if Nexis wasn’t so expensive, it would be my default search engine.

Tina Sieber

Thank you for the insight! The NEAR operator is a good one to remember.

Eweforia

Well, I’m probably old enough to know Earth, Wind, & Fire, but I wasn’t paying attention when I was young. So I copied the photo, saved it to harddrive, and Googled to find similar photos. (That’s the power of Google, which was what the article was about!) Presto, 401 similar photos, helping me deduce that the group’s name was Earth, Wind, & Fire.

Tina Sieber

Amazing what Google can do with similar image search, isn’t it? Only a few years ago that was science fiction to most of us.

null

I used to use Boolean operators all the time. It made for very specific search results. I still use them once in a while but now it seems most search engines just seem to ignore them. Too bad. Making it easier seems to have made it less useful.

Stephanie Staker

Gotta tell you that you lost me. Remember now that I am a senior citizen pushing 70 and I have NEVER figured out boolean logic. After the first few sentences of this article, I started falling asleep and, Tina, that is not your fault. It is mine. I have consistently had problems finding what I am looking for in the “real world” as well as online. My belief is that you have to know how the person who “assigned” the place where your/my info is located, thinks. Stay with me here: many years ago, I was taking classes to become a certified paralegal. One of the classes was on doing research which is really important to know in order to get a job in this field. I had one heck of a time. My logic is not the annotated statute logic so it was a constant battle for me to find the info I needed. Fortunately, in today’s digital world, all of this legal stuff is on DVD along with various search engines that “speak” to all of us. What I mean is that there are search engines out there who think like I do so “we” (the search engine and I) are able to find what I am looking for. Back to this issue of the boolean search stuff, I find that doing a search in Google (my favorite search engine) is pretty handy and sometimes scary. It generally reads my mind after I type the first few letters of my search query. The page appears magically and more often than not, what I want to know is the first thing on the list. :)

Joel Wavrecan

Earth, Wind, and Fire. An American band that has spanned the musical genres of soul, disco, R&B, funk, jazz and rock. (ref.Google)

Josh M

Great way of explaining! Thank You