Keywords are one of the most flexible ways to describe your images. This page presents some keywording strategies.

Describing images with keywords
What’s a keyword?
Hierarchical keywords
Controlled vocabulary
Internal vs. external keywording
Stock photography considerations

Describing images with keywords

Keywords are words or phrases that you associate with a picture to describe the subject matter, style, uses, or connotations of the image. These descriptions can be of great use when organizing and searching your picture collection.

Keywords can be abstract terms (like “victory”) or subject-oriented terms (like “cat” or “Maddy”). Subject-oriented terms are generally easier to apply because they require less careful consideration. Abstract terms are generally economical to apply only to the very best images, such as your highest rated ones or those that will be made available in a searchable stock photography database.

What’s a keyword?

The term “keyword” can have two meanings: it can refer to the descriptive term itself, or it can refer to the place where the keyword might live: the IPTC keywords field. It’s important to understand this difference — just because you want to associate a term with an image does not necessarily mean that you want that term to live in the IPTC keywords field.

Some of the keywording that you will do is best left as private metadata (information intended for your use but not to be shared with others). Anything you write into the IPTC keywords field can easily become embedded metadata and is therefore public.

Many people put tags in the keywords field that are more useful when placed in a field that is designed for that purpose. The location fields are a prime example. There's a big difference between the keyword Intercourse, and the city Intercourse, PA.

Hierarchical keywords

Keywords are a wonderfully flexible tool to describe what an image may be about, but they can get unwieldy on a collection-wide basis. A simple keyword list can easily climb to hundreds or thousands of terms and thus become difficult to navigate. And because most programs display keywords alphabetically, synonyms and alternate terms may not appear anywhere near each other. “Airplane,” “Helicopter,” “Jet,” and “Plane” are all terms for aircraft, but they will be widely separated in an alphabetical keyword list.

This problem is being addressed by the standardization of a metadata field to define hierarchical relationships between keyword terms. So instead of “Helicopter” and “Airplane” being part of a single flat list, they can both live inside the parent term “Aircraft.” And “Aircraft” could live inside “Vehicles” or “Transportation” (or both). Using a hierarchy makes it easy to navigate your keyword list and to keep related terms close to each other (Figure 1).

Lightroom Hierarchical Keywords FIgure 1Lightroom’s hierarchical keywords feature makes it easy to group keywords into manageable sets, rather than a long “flat” list.

The Adobe implementation of hierarchical keywords first showed up in Bridge 2.1 and Lightroom 1.1. It’s an XMP field entirely separate from the keywords field, as shown in Figure 2. It was implemented as a separate field so that it would not “break” the existing keywords field for older programs. Essentially, the hierarchical keywords field exists to provide metadata about the keywords assigned to an image. Metadata about metadata — now we’re talkin’.

Hierarchical Keywords XMP FIgure 2Here is what keywords and hierarchical keywords look like when written to metadata in the file itself. The top part (dc:subject) is the IPTC Dublin Core keywords. The bottom part is the Lightroom data that defines the relationship between the keywords. The | symbol means that the following term is a subset, so Alyson Krogh is a subset of Family, which is a subset of People.

The hierarchical keywords field, as it is currently designed, accomplishes two things. First, it offers a way to organize the keyword display to make the information easier to navigate (“Aircraft” is a child of “Vehicles”). This function is primarily oriented toward making a catalog more user-friendly. Secondly, the hierarchy can provide context for particular term (“Madeline” is a child of “Family > Krogh” rather than “Friends>Bankson”). This function is about making the context of the keyword more portable between applications.

Note that while older programs can still see the legacy (flat) keywords field, many don’t see the hierarchy field at all. And even when a program sees the two fields, it may not handle them properly since there is no clear policy on how to handle the synchronization between flat and hierarchical fields. There is also no good way to reconcile similar hierarchies that may be missing terms.

If you choose to use hierarchical keywords to organize your collection, keep a few things in mind:

  • Be as consistent as you can with hierarchies within your own collection.
  • The hierarchy will probably not translate directly from your collection to anyone else’s.
  • You may need to migrate the data structure to another tool eventually.
  • When in doubt, the flat keyword list is the most universal.

Controlled vocabulary

Keywords are most useful if they are applied in a consistent, collection-wide manner. One tool that can help to achieve consistency is a controlled vocabulary (CV). The concept is pretty simple: the list of available keywords (or any other tag, for that matter) is restricted to an approved set of terms. A CV can help ensure proper spelling and can help you keyword consistently. And by using a well-engineered CV, you add maximum value to your image collection, particularly if other people will be searching your collection or if you intend to aggregate your stock collection with other photographers (good stock photography collections are often collaborations).

You can create or purchase CVs. One is available at and another is at A purchased list is generally going to be oriented toward stock photography and will have lots of terminology that relates to how people search large stock databases. In order to use a purchased CV, you’ll need to know if the software you use supports importing a keyword list, and if the list is in a proper format for that software. Lightroom, Bridge, and Media Pro all support CV.

If you are considering a purchased list, think about the purpose of your keywords and what you hope to accomplish with your keywording. We have found, for instance, that most of our keywords are ones that would never appear on a purchased list since they are the names of our subjects, assignments, clients, and events photographed.

Most browsers and catalog software support the creation of a CV internally to some degree. Some software allows you to create a simple list of available terms. A more sophisticated approach is to restrict keywording only to approved terms, particularly for an environment in which more than one person might be doing the keywording.

Note that implementation of a controlled vocabulary is dependent on the software capability and the way the vocabulary is used. You might have a restricted vocabulary, but you might not use it consistently. Ratings, discussed next, can be an example of this. The 0–5 rating stars are a restricted vocabulary, but if you don’t use them consistently, they will not be a reliable indicator of quality. Consistency takes discipline, and it will pay you back well.

If you would like to check on the development and availability of controlled vocabulary tools, check out

Internal vs. external keywording

When you are creating your keywords, it is helpful to make the distinction between keywording for internal uses and keywording for anonymous external searches (like stock photo library searches). In most cases, internal searches require significantly fewer keywords since the search is probably much narrower. If you’re a photographer searching your own collection, you likely have a pretty good idea what you are looking for as you start. You might know you are looking for pictures you made for a particular assignment or in a particular place. In these cases, a client name or a location name might let you find these images quickly. And even a broad search like “good dog photos” does not require the same kind of rigorous keywording that would be appropriate for a stock search (where it might be appropriate to have dog, dogs, canine, pup, puppy, puppies, breed names, etc.).

If you are building and maintaining a collection of several photographers’ work (for instance, a corporate communications office), you are likely to require more extensive keywords than you would for a single photographer, but probably much less than a stock agency would. You’re likely to have a captive, motivated searcher who is willing to do a little extra work to find what he needs. And in many cases, the kinds of information he would need to search for (product or project names, employee names, and so on) are a relatively small set of terms (CV is important here to ensure names are spelled correctly and therefore easier to find).

Keywording for the kind of internal searches outlined above is very different from keywording for stock photography. In the world of stock, it’s up to you to make your images easy to find by people who don’t know the collection. The photos are generally part of a much larger pool of images, and need to float to the top quickly when someone is looking for that kind of picture, or else they won’t get sold. This generally means a much more extensive keywording process, including alternate terms, concepts, singular/plural, misspellings, and more.

Stock photography considerations

Keywords are a particularly powerful tool for stock photography collections, since most people searching a stock library are likely to enter short search terms, and in most cases the search engine will look at the keywords field. Keywording is, therefore, a very important part of preparing images for the stock photography market. The task of keywording images so they are found successfully is both an art and a science.

The keyword list maintained by most stock agencies is considered to be a proprietary trade secret since it’s one thing that helps to differentiate one service from another. If you’re keywording your images for inclusion in a stock library, it’s important to know up front whether the service will accept your keywords or if they will want you to work from their CV.

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Last Updated September 22, 2015