In the last post, we were talking about the kind of keywords to add to your photos, but this week, let’s talk about the pros and cons of flat vs. hierarchical keyword lists. Please note this only applies to Lightroom Classic, not the cloud-based version of Lightroom, which only uses a flat structure. Our next posts will apply to both versions.
On the left, we have a single long flat list of keywords, and on the right, a hierarchy of keywords nested inside other keywords. So which should you choose?
What factors should I consider when deciding to use flat or hierarchical keywords?
There are a number of factors that might influence your decision. They include:
- Simplicity – Adding new keywords to a hierarchy requires a little more forethought and logic, whereas adding random keywords to a flat list can be done on-the-fly.
- Universally Understood – Flat keywords are understood by most photographic software. If you create a hierarchy in Lightroom, it writes out the keywords as both flat and hierarchical, so if you move to other software, your keywords will still go along for the ride, but probably as a flat list. This is also the case should you later decide to migrate to Lightroom (cloud-based).
- Editing in Other Programs – In addition to moving to other software in the future, you can also run into issues with keyword hierarchies when exporting photos to edit in other software and then adding them back into the catalog. If some keywords are set to “Don’t Export” (often used for parent keywords like who, what, when), when the photos come back into Lightroom’s catalog, their keywords will be listed as new root level keywords.
- Scrolling – If you start adding a lot of keywords to your photos, a flat keyword list can become very long very quickly. If you’re on Windows, you may even run into a bug/limitation, which prevents the Keyword List showing more than around 1600 keywords at one time. A keyword hierarchy allows you to collapse the list, so you’re seeing fewer keywords at any time.
- Automatic Entry – One of the major advantages to a hierarchy of keywords is that parent keywords are automatically added to the photos. For example, if I tagged a photo with “my house”, the parent keywords “Southampton, Hampshire, England, UK, Europe” would automatically be added to the photo too. This can save a lot of time.
- Time Spent Reorganizing – If you don’t start out with a clear idea of how you’ll organize your keyword hierarchy, you can spend a lot of time organizing and reorganizing the keywords into a list you like.
- Multiple Catalogs – If you use more than one catalog (and we considered the pros and cons in this earlier post), and you reorganize a hierarchical keyword list in one catalog, you’ll end up with a massive mess and duplicate keywords when you try to merge that back into another catalog. This can even apply to travel catalogs.
- Migration to Lightroom (cloud-based) – If you are considering this, then you will end up with flat keywords anyway, so better to plan that from the start.
Your final decision will probably depend on how many keywords you think you’re going to add. If you’re shooting for stock photography, a hierarchy is the obvious choice. If you’re shooting for your own use, a flat list may be a simpler choice.
There is, of course, a compromise. You could have a very simple hierarchy, with a few parent keywords and all of the other keywords nested directly inside, for example, your parent keywords might be who, what, where, when, why, how. These can also act as a prompt, to remind you to add at least one keyword for each. You can even create a smart collection to show photos that don’t have at least one keyword under each heading.
If you decide on a hierarchical keyword list, draft your list in a text editor or spreadsheet, or even on a piece of paper. By doing so, you’ll save yourself a lot of time rearranging your keyword list later. One more tip… when adding People keywords, don’t try to create a family tree. Since most of us have more than one parent, it gets messy fast!
In the next post, we’ll start on the practicalities – how to create keywords, apply them to your photos and, most importantly, how to use them to find the photos again later.
For extensive information on Lightroom Classic, see Adobe Lightroom Classic – The Missing FAQ.
If you have the Photography Plan, then as well as Classic you have access to the Lightroom cloud ecosystem including the mobile apps and web interface. For more information on these apps, see Adobe Lightroom – Edit Like a Pro.
Note: purchase of these books includes the first year’s Classic or cloud-based Premium Membership (depending on the book purchased), giving access to download the latest eBook (each time Adobe updates the software), email assistance for the applicable Lightroom version if you hit a problem, and other bonuses.
We also have a special bundle offer for the two books. This includes Premium Membership for the first year as described above for the whole Lightroom family!
Originally posted 27 March 2017, updated May 2020.