IAB Content Taxonomy 3.1: Category List and Structure
A practical guide to the current IAB Content Taxonomy: how the four tiers fit together, what each top-level category covers, which fields the official file contains, and how the categories are applied to whole domains for contextual targeting.
What the IAB Content Taxonomy is
The Content Taxonomy is a shared vocabulary for describing what a page, app, video or podcast is about. It lets a publisher, an SSP, a DSP and a verification vendor all say "this inventory is about Personal Finance" and mean the same thing.
A tree of subjects
Categories sit in a hierarchy. Each row has an ID, a parent ID and a name, so software can roll a narrow subject up to its broad parent.
An industry standard
IAB Tech Lab maintains it. Ad platforms reference it in bid requests and in campaign settings, which is why buyers ask for data in this format.
Topic, not product
It describes content. The product being advertised is described by a sister standard, the Ad Product Taxonomy, covered in our content taxonomy vs ad product taxonomy guide.
Version timeline
Version 1.0, the first flat list with short "IAB" codes. IAB Tech Lab deprecated it in 2020.
Version 2.0 introduced a deeper hierarchy and numeric IDs.
Versions 2.1 and 2.2 refined the 2.x tree. The 2.x line is now being phased out.
Version 3.0 restructured the tree, removed some 2.x rows and was released together with a separate Descriptive Vectors file.
Version 3.1, a minor update focused on the genres list. It is the current release.
The detailed differences between the two version 3 releases, plus migration notes, are on our IAB Content Taxonomy 3.0 vs 3.1 page.
How the four tiers work
Every category row carries up to four tier values. Tier 1 is the broad subject. Each lower tier narrows it. Many branches stop at tier 2 or 3; only a minority go all the way to tier 4.
| Level | Rows in 3.0 | What it is good for | Typical use |
|---|---|---|---|
| Tier 1 | 36 | Broad reach, simple reporting | Inventory dashboards, coarse include lists, rough audience splits |
| Tier 2 | 322 | The working level for most campaigns | Contextual line items, category bid modifiers, publisher packaging |
| Tier 3 | 275 | Precise niches with clear intent | Endemic advertisers, sponsorships, research segments |
| Tier 4 | 70 | Very specific leaves in a few branches | Finance, automotive and technology niches where buyers need fine detail |
The rows add up to 703 in version 3.0. The 3.1 file adds Thriller as a tier 2 entry under Genres, which brings the total to 704.
Fields in the official file
Unique ID
The stable key for each category. Most IDs are numbers, and some newer ones are short alphanumeric codes. Store the ID, not the name, in your systems.
Parent
The ID of the row one level up. Tier 1 rows have no parent. Following parents lets you roll any leaf up to its top-level subject.
Name
The human label of the row itself, for example "Venture Capital". Names can repeat in different branches, which is another reason to key on IDs.
Tier 1 to Tier 4
The full path spelled out, one column per level. Handy for spreadsheets and for filtering without walking the parent chain.
Extension
An extra column that flags some rows with "SCD", short for sensitive category data. Treat flagged rows with care in targeting and in privacy reviews.
Vectors (separate file)
Version 3 moved non-topic attributes, such as format or channel style, into a Descriptive Vectors file, so topic rows stay about subject matter only.
Top-level categories in IAB Content Taxonomy 3.1
The table lists every tier 1 entry, how many rows sit in its branch (the tier 1 row included, counted on the 3.0 tree), a few of its tier 2 children and the kinds of websites that usually land there. Descriptions are our own summaries.
| Tier 1 | Rows | Example tier 2 children | Sites that typically fit |
|---|---|---|---|
| Attractions | 12 | Amusement and Theme Parks, Museums & Galleries, Zoos & Aquariums | Venue sites, local leisure guides, ticketing for places to visit |
| Automotive | 41 | Auto Buying and Selling, Auto Parts, Motorcycles | Dealers, car review sites, parts shops, owner forums |
| Books and Literature | 5 | Fiction, Poetry, Comics and Graphic Novels | Book review blogs, author sites, reading communities |
| Business and Finance | 71 | Business, Economy, Industries | Trade press, B2B service firms, economic news, company sites |
| Careers | 9 | Job Search, Remote Working, Vocational Training | Job boards, career coaching, apprenticeship portals |
| Communication | 1 | No children | Messaging and communication software sites (top level in the 3.1 file, see note below) |
| Crime | 1 | No children | Crime reporting and true crime coverage |
| Disasters | 1 | No children | Emergency news, disaster relief information |
| Education | 18 | Online Education, Language Learning, Homeschooling | Schools, course platforms, study help, tutoring |
| Entertainment | 37 | Movies, Music, Television | Film and TV sites, music publications, streaming guides |
| Events | 4 | Awards Shows, Business Expos & Conferences, Fan Conventions | Event organisers, conference sites, convention listings |
| Family and Relationships | 15 | Parenting, Marriage and Civil Unions, Eldercare | Parenting blogs, family advice, relationship guidance |
| Fine Art | 9 | Dance, Design, Opera, Theater | Galleries, arts organisations, performing arts venues |
| Food & Drink | 13 | Cooking, World Cuisines, Alcoholic Beverages | Recipe sites, food magazines, beverage brands |
| Genres | 31 | Comedy, Documentary, Horror, Thriller | Mainly used for video, audio and CTV programming rather than websites |
| Healthy Living | 16 | Fitness and Exercise, Nutrition, Wellness | Fitness blogs, diet and wellbeing content |
| Hobbies & Interests | 35 | Arts and Crafts, Collecting, Genealogy and Ancestry | Hobby communities, craft shops, specialist clubs |
| Holidays | 2 | National & Civic Holidays | Holiday calendars and seasonal guides |
| Home & Garden | 12 | Gardening, Home Improvement, Smart Home | DIY sites, home decor, garden centres |
| Law | 1 | No children | Legal information and law firm sites |
| Medical Health | 38 | Diseases and Conditions, Pharmaceutical Drugs, Surgery | Clinics, health reference sites, patient resources |
| Personal Celebrations & Life Events | 11 | Wedding, Birthday, Graduation | Wedding planners, party guides, event vendors |
| Personal Finance | 31 | Consumer Banking, Insurance, Retirement Planning | Banks, comparison sites, money advice blogs |
| Pets | 10 | Dogs, Cats, Veterinary Medicine | Pet shops, vets, breed clubs, pet care advice |
| Politics | 4 | Elections, Civic affairs, Political Issues & policy | Political news, campaigns, civic information |
| Pop Culture | 9 | Celebrity Relationships, Celebrity Style, Humor and Satire | Celebrity news, gossip, satire sites |
| Real Estate | 12 | Houses, Apartments, Office Property | Property portals, agencies, commercial real estate |
| Religion & Spirituality | 11 | Christianity, Islam, Buddhism, Astrology | Faith communities, spiritual practice, astrology content |
| Science | 10 | Space and Astronomy, Genetics, Weather | Science news, research institutes, weather services |
| Sensitive Topics | 12 | Online Piracy, Terrorism, Obscenity and Profanity | Content most brands avoid; used chiefly for exclusion lists |
| Shopping | 11 | Coupons and Discounts, Grocery Shopping, Holiday Shopping | Deal sites, online stores, gift shops |
| Sports | 69 | Soccer, Basketball, Golf, Fantasy Sports | Sports news, clubs, leagues, betting tips, equipment |
| Style & Fashion | 44 | Beauty, Men's Fashion, Women's Fashion | Fashion retail, beauty blogs, style magazines |
| Technology & Computing | 47 | Artificial Intelligence, Computing, Consumer Electronics | Tech news, software vendors, gadget reviews |
| Travel | 27 | Travel Locations, Travel Type, Travel Accessories | Travel agencies, destination guides, booking sites |
| Video Gaming | 24 | Console Games, Mobile Games, eSports | Game studios, gaming news, eSports coverage |
| War and Conflicts | 1 | No children | Conflict coverage and military history |
Note on Communication: in 3.0 this row sat at tier 4 under Technology & Computing > Computing > Computer Software and Applications. The published 3.1 file lists it with no parent, so it appears as a top-level entry. Its ID did not change.
Need every tier, not just the top level? Our IAB taxonomy reference with JSON and CSV downloads lists all rows with IDs and parents. A shorter overview of each branch is on the IAB categories list page.
Three parts of the tree that need special handling
Most branches describe ordinary subjects. Three areas behave differently and cause most of the questions we get from data buyers.
Genres
Genres describe the style of a programme, such as Comedy or Documentary, not its subject. They matter most for CTV, video and audio. A website rarely carries a genre as its main label.
When you target CTV inventory, combine a genre with a subject. "Documentary" plus "Science" is far more useful than either alone.
Sensitive Topics
This branch groups subjects that many advertisers exclude, from explicit content to hate speech and piracy. Most buyers use it as a block list rather than for targeting.
Exclude only the rows you really need to. Blocking the whole branch can remove legitimate news coverage.
SCD-flagged rows
Rows marked SCD cover areas where personal data rules apply, such as health conditions or religion. Targeting individuals on these subjects can raise legal issues in many regions.
Using them as context, on the page or domain, is different from building a profile of a person. Check with your privacy team.
How to use IAB 3.1 for contextual targeting
Contextual targeting places ads next to content that matches the message, without tracking the person. The taxonomy is the common language that makes these settings portable between platforms. A workable process looks like this.
Start from the product, then pick subjects
List the subjects your customer reads before buying. A running shoe brand might choose Sports > Track and Field, Healthy Living > Fitness and Exercise and Style & Fashion > Men's Fashion or Women's Fashion.
Choose the depth per branch
Use tier 2 for reach and tier 3 or 4 for intent. Mixing depths is fine, as long as you store the IDs and know which parent each leaf rolls up to.
Build the exclusion list next to the inclusion list
Decide which Sensitive Topics rows to block and whether any adjacent subjects, such as Disasters or Crime, are off limits for this campaign. Write the rules down so reviews are consistent.
Translate the IDs for each platform
Platforms accept IAB IDs in different ways. In OpenRTB, a taxonomy indicator field tells the receiver which taxonomy and version a list of category codes belongs to, so make sure your codes and the declared version match.
Turn subjects into domain lists
Many buying tools work best with domain include and exclude lists. Pull every domain whose ranked categories contain your chosen IDs, then filter by popularity and country.
Spot check before launch
Look up a sample of domains from the list with our domain category checker. Ten minutes of review catches odd edge cases before money is spent.
Measure by category, not just by campaign
Report results by tier 1 and tier 2. You will quickly see which subjects drive outcomes and which only add cheap impressions.
For a full advertiser view of the trade-offs, read contextual targeting vs behavioral targeting, and see the contextual targeting use case for how platforms embed category data.
How our database applies IAB version 3 to domains
The URL Categorization Database assigns IAB version 3 categories to whole domains. Each domain is categorized from its site content, then reviewed and validated. A domain can carry several categories, ranked by how much of the site each one describes.
- Ranked IAB v3 categories, down to tier 4 where the content supports it
- IAB v2 categories in a separate column for systems still on the older tree
- Web filtering categories for brand safety and policy rules
- Popularity data, so lists can be cut to the domains that carry real traffic
- More than 1,900 audience personas inferred from site content
- Delivered as CSV, JSON or Parquet files that run in your own systems, with a lookup API included
How both IAB columns live side by side is described in dual taxonomy categorization.
Illustrative layout only. Field names in the delivered files are described in the data dictionary that ships with a licence.
Domain level or page level?
| Question | Domain-level labels | Page-level labels |
|---|---|---|
| Speed | Instant lookup from a local file | Needs a call or a crawl per URL |
| Coverage | Every domain in the file is labelled before the bid arrives | New pages may be unlabelled at first |
| Precision | Best for focused sites and for exclusion lists | Better for very broad portals and news sites |
| Privacy | No user data involved | No user data involved |
| Best fit | Include and exclude lists, supply filtering, research | Article-level targeting on large publishers |
Most buyers combine both: domain labels for the bulk of decisions and a closer look at the handful of big portals where one domain covers everything.
Practical tips for working with the 3.1 list
IDs Key everything on IDs
Names are for people. IDs are for systems. Several names appear in more than one branch, and a future release may rename a row while keeping its ID.
Version Record the version
Store the taxonomy version next to every category list you exchange. A 2.x code and a 3.x code can look alike and mean different things.
Roll-up Keep a parent map
A small table of child ID to tier 1 ID makes reporting easy. You can build it once from the Parent column.
Depth Do not over-narrow
Tier 4 leaves can be very small. If a campaign struggles to spend, step back to the tier 3 or tier 2 parent before widening anything else.
Mix Pair topic with quality
A category tells you what a site is about, not whether it is a good place for ads. Combine it with popularity and site quality checks, for example when screening made for advertising sites.
Review Revisit lists monthly
Websites change topic, expire or get repurposed. Refreshing domain lists from current data keeps targeting aligned with what the sites publish today.
Frequently asked questions
When was IAB Content Taxonomy 3.1 released?
IAB Tech Lab released version 3.1 in December 2024, together with guidance on CTV genres. It followed version 3.0 from June 2022.
How many categories are in IAB 3.1?
The 3.1 file has 704 category rows. Version 3.0 has 703. The difference is the new Thriller genre. Descriptive vectors are kept in a separate file and are not counted here.
How many top-level categories are there?
Version 3.0 has 36 tier 1 entries. In the 3.1 file, Communication also appears without a parent, which gives 37 entries at the top level.
Is 3.1 compatible with 3.0?
For practical purposes, yes. It is a minor release that keeps the 3.0 IDs. Moving from 2.x to 3.x is a bigger step, because 3.0 removed and restructured rows.
Can I download the full list?
Yes. The taxonomy page offers JSON and CSV exports of the IAB version 3 and version 2 lists that appear in our data, at no cost.
Do you label pages or domains?
The database labels domains. Each domain carries several ranked IAB categories, which suits list building, supply filtering and research at scale.
Get IAB version 3 categories for 120 million domains
Ranked IAB v3 and v2 categories, web filtering labels, personas and popularity in one file that runs inside your own stack. Pick a size that fits your workload.
See database plans Explore the databaseIAB and IAB Tech Lab are trademarks of the Interactive Advertising Bureau. They are used here only to identify the standard discussed. URL Categorization Database is not affiliated with, sponsored or endorsed by IAB or IAB Tech Lab. Category names are listed as facts; all descriptions on this page are our own.