Boolean Search Explained: The Meaning, 12 Operators and Where Each One Works

By Sparsh Goyal, Founder at The Cognitive. Published 2026-10-04 · Last updated 2026-10-05

• Boolean search joins keywords with AND, OR, NOT, quotes and parentheses so only results that fit the logic come back, and each engine supports a different subset of operators.
• LinkedIn rejects the asterisk wildcard, Google documents a minus sign instead of NOT, Bing reads only the first 10 terms, and Greenhouse needs Full Text Search switched on.
• The Cognitive reads a plain-English brief into editable filters across ~900M public profiles, so you can skip the string for sourcing and keep operators for your ATS.

Boolean search is a way of searching that joins keywords with operators, so the engine returns only the results that fit your logic. The core 5 operators are AND, OR, NOT, quotation marks and parentheses: AND narrows, OR widens and NOT excludes. Each engine supports a different subset. LinkedIn rejects the asterisk wildcard, Google documents a minus sign instead of NOT, and Greenhouse and Bullhorn both accept the asterisk. I checked every cell below against each engine's own help page, read on 4 October 2026.

This page starts with what Boolean search means and where the name comes from, then turns into a reference card: one matrix of 12 operators across Google, Bing, LinkedIn, LinkedIn Recruiter, Indeed, Greenhouse and Bullhorn, the order each engine reads them in, the syntax mistakes that break a string without telling you, and a printable cheat sheet. The operators still matter. In Gem's 2026 benchmarks, sourced candidates are nearly 8 times more likely to be hired than inbound applicants, and the string is how most sourcing starts.

Full disclosure: I run The Cognitive, which reads a plain-English brief instead of a string. I say where that replaces operators and where it does not, near the end.

What is Boolean search?

Boolean search means combining keywords with logic so the engine returns only the records that make your statement true. A record either contains a term or it does not, and the operators decide which combinations count.

The name comes from George Boole, the English mathematician who lived from 1815 to 1864. His 1854 book, An Investigation of the Laws of Thought, turned logic into an algebra with 2 values, true and false. Every search box that reads AND, OR and NOT is running his rule.

A Boolean query, also called a Boolean string, is the statement itself: the full line of keywords and operators you paste into the box, such as "clinical research associate" AND GCP NOT intern. You save it, adjust it for each engine and reuse it.

Boolean search is older than recruiting. University libraries still teach it for article databases and catalogues; MIT Libraries' database search tips cover the operators, phrase searching and truncation. Recruiters took it to LinkedIn, job boards, ATS keyword boxes and Google, and it became the backbone of candidate sourcing. On Google it is usually called X-ray search: Boolean logic aimed at one site with the site: operator. Our LinkedIn X-ray search guide covers LinkedIn, and the X-ray search guide for other sites covers GitHub, Kaggle, Dribbble and the rest.

The operators fall into 3 groups, and they behave very differently across engines:

• Logic operators: AND, OR, NOT, and the minus sign some engines use for NOT.
• Grouping and matching: quotation marks for exact phrases, parentheses for grouping, the asterisk for word endings, NEAR or AROUND for proximity.
• Field operators: site:, intitle:, inurl: and filetype: on web search engines, and the title:, company: and school: commands recruiters still pass around for LinkedIn.

For the recruiting strategy, such as which requirements deserve an AND, read our guide to Boolean search in recruitment. The rest of this page is the reference.

The 12 Boolean search operators, at a glance

Here is what each operator does and one example of it. Support varies by engine; the matrix in the next section says exactly where each one works.

2 notes before you copy anything. The NEAR and AROUND example is the form you will see in sourcing guides, and none of the 7 engines in this guide documents it. The title:, company: and school: commands have the same problem on LinkedIn today, which I explain below.

Which Boolean operators does each search engine support?

I read each engine's own help page on 4 October 2026 and marked a cell "Yes" only where that page names the operator. "Not documented" means the page does not mention it. It might still work today; nobody has promised it will keep working. "Not supported" means the engine says so in writing.

Google, Bing and LinkedIn

Indeed, Greenhouse and Bullhorn

What the help pages actually say

Google lists 6 operators on its Refine Google searches page: quotes, site:, a leading minus, before:, after: and filetype:. That is the whole list. OR, parentheses, intitle:, inurl: and AROUND are absent, so treat them as undocumented. Google's Search Central page adds a warning worth remembering: operators "are bound by indexing and retrieval limits". A site: search shows what Google has indexed, and that is never the whole site.

Bing documents the most. Its advanced search options page covers AND, OR, NOT, quotes and parentheses, and its advanced search keywords page adds intitle:, inbody:, site:, filetype: and loc:. One line changes how you write for it: "Only the first 10 terms are used to get search results." A 25-term string on Bing is mostly decoration.

LinkedIn search takes Boolean "directly into the main search bar", per its Boolean help page. It accepts AND, OR, NOT, quotes and parentheses, and it says plainly that it "does not support braces { }, brackets [ ], angle brackets < >, or wildcards like asterisks *".

LinkedIn Recruiter and Recruiter Lite accept the same operators, per the Recruiter help page. You can type quoted searches and Boolean "in the Job titles, Companies, or Keywords filters". The Must have, Can have and Doesn't have dropdowns map to AND, OR and NOT. The Project filter takes no Boolean at all. If you are deciding between the 2 seats, our Recruiter Lite review sets out what the cheaper one leaves out.

Indeed explains Boolean for its resume search in a hiring guide updated 28 August 2025: AND, OR, NOT, quotation marks, and "parentheses and brackets" for grouping, typed in capital letters. It is the one engine here that names square brackets as grouping symbols. LinkedIn treats the same brackets as plain text. Our walkthrough of Indeed resume search covers access, cost and strings for that database.

Greenhouse Recruiting needs a switch first. Per its support article (updated 2 March 2026), you open All Candidates and toggle Full Text Search. The article lists the feature for its Core, Plus and Pro tiers. After that, AND, OR, NOT, quotes, parentheses and the * wildcard all work, and the search reaches resumes, notes and scorecards.

Bullhorn ATS uses AND NOT where other engines use NOT, per its Understanding Boolean Logic guide. It supports the asterisk ("Manag*" returns manager, managing and management) and warns that its extra criteria filters "don't support OR searches directly". If you are pricing the ATS itself, our Bullhorn pricing guide explains how it is sold.

The ATS rows matter more than they used to. Gem's 2026 report says 46% of sourced hires now come from rediscovered candidates already in a company's CRM or ATS, up from 26% in 2021. A clean string in Greenhouse or Bullhorn is often the fastest search you will run all week, and the core of any talent rediscovery routine.

Do title:, company: and school: still work on LinkedIn?

None of LinkedIn's current help pages documents them. I read the LinkedIn search, Boolean and Recruiter help pages on 4 October 2026, and none lists title:, company:, school:, firstname: or lastname:. The 2017 LinkedIn blog post that introduced them now redirects to LinkedIn's general member blog.

Sourcing forums report that they stopped working in the free search bar and may still respond in Recruiter. I could not confirm that on a LinkedIn page, so I would not build a saved search on them.

The documented route in LinkedIn Recruiter does the same job. Put your title group in the Job titles filter, your employers in Companies and your universities in Schools, then set each to Must have, Can have or Doesn't have. Job titles and Companies accept quotes and Boolean, so "data engineer" OR "analytics engineer" typed into Job titles is the supported version of a title: command. The filters also survive the next product update, which an undocumented command might not.

In what order are Boolean operators read?

Most engines read quotes first, then parentheses, then NOT, then AND, and OR last. LinkedIn publishes exactly that order on its Boolean page. Bing publishes nearly the same one: parentheses, quotes, NOT, AND, OR. Both say OR has the lowest precedence, and Bing tells you to "enclose OR terms in parentheses when combined with other operators".

Here is why that matters. Take this string, written by someone who wants developers or engineers who know Python:

developer OR engineer AND python

Because AND is read before OR, the engine reads it as:

developer OR (engineer AND python)

Every developer comes back, Python or not. The fix is 2 characters:

(developer OR engineer) AND python

My rule: any time OR sits next to AND or NOT, the OR group gets parentheses. That holds on every engine in the matrix. On Google, where parentheses are undocumented, run the string once and check page 1 before you save it.

What are the most common Boolean search mistakes?

These 7 break a string without an error message. You get results, so nothing tells you the logic was wrong.

1. Smart quotes pasted from Word or Google Docs

Word processors turn straight quotes into curly ones. Greenhouse warns that pasted quotation marks "will be treated as "smart quotes" which are not compatible with Boolean search". Keep your strings in a plain text editor, or retype the quotes in the search box.

2. Lowercase and, or, not

LinkedIn says you "must type them in uppercase letters". Bing goes further: lowercase not and or are ignored "as stop words". A lowercase or quietly turns your list of synonyms into a list of requirements.

3. Square brackets and curly braces

Templates written for other tools often group with [ ] or { }. LinkedIn treats both as "ordinary characters and will not group terms". Indeed accepts brackets. Use round parentheses everywhere and you never have to remember which is which.

4. A space after the colon

Google's example is the clearest: "A search for [ site:nytimes.com ] will work, but [ site: nytimes.com ] won't." Bing says the same for all its keywords. The same habit is why title: commands fail when someone types title: engineer.

5. Too many operators for the engine

LinkedIn's free search caps the number of Boolean operators in one query and does not publish the number, per its Boolean query limitations page. Recruiter and Recruiter Lite have "no limit". Sales Navigator allows "a maximum of 15". Bing reads only the first 10 terms. If a long string returns oddly broad results on free LinkedIn or Bing, cut it in half before you blame the market.

6. Over-nesting

Brackets inside brackets inside brackets are where unmatched parentheses hide. I keep strings to one level of grouping: a title group, a skill group or 2, and an exclusion group, joined by AND. If a string needs a 3rd level, it is usually 2 searches.

7. NOT used as a cleanup tool

Bullhorn says AND NOT "should be used with caution, because it eliminates candidates that have that keyword in any of the areas you are searching in". LinkedIn's Recruiter page gives the same advice: "be specific and inclusive rather than vague and exclusive". Exclude intern and you also drop the senior engineer whose profile says she mentors interns.

Boolean search query optimization techniques

Optimizing a Boolean query means changing one thing at a time and reading what each change does. The 4 techniques that do the work:

• Start broad. Run the title group alone first. If that returns too few people, no amount of AND will fix it.
• Add synonyms before requirements. Candidates describe the same job 4 or 5 ways. Each missing spelling is a group of people you never see.
• Add exclusions last, and only from evidence. Read the wrong results, find the word they share, exclude that word.
• Test by reading. Read the first 20 results after every change and mark each yes or no. A result count tells you volume; reading tells you whether the string works.

Reading matters because volume is the problem. Ashby's 2026 report says the average recruiter is processing 291 applications per hire, compared to roughly 100 in early 2021. A loose string rebuilds that pile in your sourcing tab.

One string, refined through 4 versions

The role: a clinical research associate for a contract research organisation, searched in the LinkedIn Recruiter Keywords filter. I wrote these by hand and have not published result counts, because counts change daily and depend on your network.

Version 1: start broad. One exact title, nothing else.

"clinical research associate"

The gap shows up as soon as you read: people doing this job also go by CRA, clinical monitor or site monitor. Version 1 misses all of them.

Version 2: add synonyms. The title group widens with OR, inside parentheses so it can take an AND later.

("clinical research associate" OR CRA OR "clinical monitor" OR "site monitor")

Version 3: add one must-have. I picked Good Clinical Practice training as the requirement. Profiles write it 2 ways, so it goes in as its own OR group.

("clinical research associate" OR CRA OR "clinical monitor" OR "site monitor") AND (GCP OR "Good Clinical Practice")

Version 4: exclude from evidence, then test. Reading version 3 would surface 2 kinds of noise. CRA also stands for Community Reinvestment Act, so bank compliance staff come back. Recruiters who hire CRAs list the title too.

("clinical research associate" OR CRA OR "clinical monitor" OR "site monitor") AND (GCP OR "Good Clinical Practice") NOT ("Community Reinvestment" OR recruiter OR intern)

Then read 20 again. If strong people are missing, the exclusion is too wide, so remove one term and rerun. Moving the same search to Google means swapping NOT for minus signs and adding a site: path:

site:linkedin.com/in/ ("clinical research associate" OR "clinical monitor") ("GCP" OR "Good Clinical Practice") -"Community Reinvestment" -recruiter

OR and parentheses are undocumented on Google, so test that version before you trust it. For 51 more strings by role, see our Boolean search strings examples. For LinkedIn-only technique, read the LinkedIn Boolean search guide. For Google, read the Google X-ray search guide.

Printable Boolean search cheat sheet

One screen, every engine. Print this table, or save it next to your saved searches.

The "A space" cell for Google is the convention X-ray guides rely on, and Google's help page does not state it. Bing's page does, in so many words: "all searches are AND searches". If you would rather not write strings at all, our free Boolean search generator writes separate versions for LinkedIn Recruiter, LinkedIn and Google X-ray and checks the brackets and quotes for you.

Which operators will you never need?

If you source with The Cognitive's AI candidate search, you skip the string. You type the role the way you would brief a colleague, and it reads the brief into editable filters across ~900M public profiles. I tested it with "Senior backend engineer with 5+ years of Go who has built payments systems, Remote EU". The filters it produced included "Remote EU", read as Germany plus 7 other countries. In operator terms, that is a title group, a skill requirement and a location OR group of 8 countries that I never typed.

Here is how the parts of a string map to what it does instead:

• OR groups of synonyms come from the brief. You edit the filters if it read something wrong.
• AND requirements become must-haves. Everyone found is judged against them, and anyone who misses one drops below the people who meet them. Nobody is removed, so a NOT that was too wide cannot silently cost you a candidate.
• Reading 20 results gets faster, because each card opens with a "Why this match" line giving 1 or 2 reasons traced to the profile.
• Loosening a string that returns nobody happens on its own: when the pool is thin, the search relaxes its softest filters and says what it broadened.

Boolean search and AI candidate search fail in opposite directions. A string returns exactly what you asked for, so the synonym you forgot costs you everyone who uses it. A plain-English search infers the synonyms, which is why it recovers people a string misses, and why the match reason matters more than the count. Our comparison of natural language candidate search tools tests that trade-off across 7 products.

Credits are simple: 1 per candidate a search returns, 5 to reveal an email and 10 to reveal a phone number, charged only when a value comes back. AI Sourcing starts at $49/month.

The operators you will still need are the ATS ones. The Cognitive does not search your own ATS history, so the Greenhouse and Bullhorn columns above stay useful for rediscovering past applicants.

Type the role instead of the string One plain-English sentence, read into editable filters and judged against your must-haves across ~900M public profiles. Start free

Who is The Cognitive built for?

The Cognitive is built for recruiters and founders who need people from outside their own database and would rather spend their time reading profiles than debugging parentheses. It suits agency recruiters juggling several roles, in-house teams without a LinkedIn Recruiter seat, and anyone hiring in a field whose vocabulary they do not yet know. That last case is where a string fails quietly, on the synonym you never thought to add.

It works next to the tools in this guide:

• Keep your ATS search in Greenhouse or Bullhorn for past applicants. The Cognitive connects to 60+ ATSs, and it writes a note with the score, summary and report link back only for candidates imported from the ATS.
• Keep LinkedIn Recruiter if you rely on InMail. The Cognitive sends email and SMS sequences on the Sourcing Pro plan and has no InMail.
• Keep this cheat sheet for Google X-ray and quick checks in any search box.

There is a free trial with 100 sourcing credits.

Run your hardest open role as a brief Describe it in one sentence, see who meets every must-have, then reveal verified contacts for the people you pick. Start free

Sources

• Wikipedia, George Boole, read on 4 October 2026.
• MIT Libraries, Database Search Tips, read on 4 October 2026.
• Google Search Help, Refine Google searches, read on 4 October 2026.
• Google Search Central, Overview of Google search operators, last updated 10 December 2025, read on 4 October 2026.
• Microsoft Support, Advanced search options (Bing), read on 4 October 2026.
• Microsoft Support, Advanced search keywords (Bing), read on 4 October 2026.
• LinkedIn Help, Use Boolean search on LinkedIn, read on 4 October 2026.
• LinkedIn Help, Boolean query limitations, read on 4 October 2026.
• LinkedIn Recruiter Help, Use Boolean to filter search results in Recruiter and Recruiter Lite, read on 4 October 2026.
• Indeed for Employers, What is Boolean search?, last updated 28 August 2025, read on 4 October 2026.
• Greenhouse Support, Search candidates using Boolean queries, last updated 2 March 2026, read on 4 October 2026.
• Bullhorn Knowledge Base, Understanding Boolean Logic, read on 4 October 2026.
• Gem, Key takeaways from the 2026 Recruiting Benchmarks Report, read on 4 October 2026.
• Ashby, Recruiter productivity trends report, read on 4 October 2026.

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