Tagging is one of the most powerful yet challenging features of personal knowledge management systems. In this post, I’ll explain what tags can do for you, some of the challenges involved, and how you can use them to your advantage.

The way to understand tags is to consider them in distinction to how most people have traditionally organized stuff with computers: by using containers such as folders or groups. Folders can contain many items (i.e., documents, emails, other folders, etc.), but one item must live in at most one folder. Thus, a file-folder system results in a tree hierarchy.

Tags don’t have this constraint. You can add as many tags to an item as you want. Each time you do, the item becomes part of the group of items that also have that tag. This results in a richer (and more complex) set of relationships between items. And these items might “live” in separate apps or systems; tags bring them together. As my friend Karl Fast puts it (I’m paraphrasing): folders are for dividing; tags are for joining.

Thus, tagging is very powerful: it allows you to find things more efficiently, discover unexpected relationships between items, manage complex workflows, and more. And many apps let you use tags in addition to folders, so you get the best of both. But there are challenges:

  • It’s easy to go overboard by adding many tags to an item. This creates friction when organizing items since you must consider what tags to add.

  • As a result, you can end up with lots of tags to manage, including minor variations of the same term. For example, the computer doesn’t know that “book” and “books” (i.e., plural) refer to the same thing.

  • But it might be even worse: “book” and “books” might not refer to the same thing in your system. So you must remember the distinction between them at the time of tagging. This also adds friction to the capture/organization parts of the process.

  • It can be hard to maintain consistency. While many apps assist you by auto-completing tags (i.e., letting you select from previously-used tags), typos in free-form text-based tags (i.e., made by prepending a hash mark to the word) can lead to a proliferation of unintended variations.

  • Multiple apps might use tags but not synch tag collections with each other, forcing you (the user) to manage parallel sets of tags. This is becoming more of an issue as PKM apps proliferate.

To summarize: tags are very powerful but can be challenging to use. Using them effectively requires discipline and mindfulness — but it’s worth it. Here are a few pointers that will help you use tags more effectively:

  • Less is more: opt for between one and three tags per item. More than that, and you’ll spend inordinate amounts of time tagging things. Again, this adds friction.

  • Decide on a text format for your tags and stick to it. All lowercase? camelCase? CapitalCameCase? flatcase? snake_case? kebab-case? Etc. (This choice might not be entirely up to you; some apps prefer some types over others.)

  • Decide on grammatical rules and stick to them. For example, will you tag an item representing a book as #books, since it belongs to the “books” group, or #book, since it describes a single book?

  • Decide what you’ll use tags for and stick to those decisions.

Here are a few ideas on ways to use tags:

  • As semantic descriptors, for describing what something is. E.g., #book = “this item represents a book.”

  • As grouping descriptors, for associating items with other related items. E.g., #dulynoted = in my case, this means “this item is related to the book I’m working on.”

  • As state indicators, for setting up workflows. E.g., #unread = “you haven’t gotten to this one yet.”

  • As action flags, which are also useful for workflows. E.g., #todo = “this is an item you must act on somehow.”

Of course, you can mix tag categorization schemes. Then you can use search and/or smart folders or groups to build punch lists, keep track of things you’d like to read or buy, organize your projects, etc. For example, I commonly tag some bookmarks as both #book (semantic) and #wishlist (grouping) — you can guess what this means. If I buy the book later, I either remove the #wishlist tag or delete the bookmark altogether.

Again, powerful stuff. And it can also be fun! But as I mentioned above, don’t go overboard. Avoid adding more than three or so tags per item. Keep group, workflow, and state indicators simple. And be consistent! You don’t want to continually innovate or improvise when tagging.

What about you? Are you using tags to manage your personal information? What have you found helpful or challenging? Please let me know; your feedback will help me develop this subject for Duly Noted.


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