It’s cliché, but true—a picture does paint a thousand words. This is an important message to remember when writing any sort of user documentation, such as an installation guide or an instruction manual. A document that makes judicious use of images and diagrams will be much easier to understand than one that is composed entirely of text descriptions.

I observed this first-hand years ago, when a junior programmer at one company was asked to update the software installation manual for their machine controllers. One of the first things he did was to strip away all the screen capture images, reducing the entire document to plain text. “These images are just silly!” he said. “They take up space, and they’re just not necessary. I trust that anyone who reads this document will be smart enough to figure it out.”

This turned out to be a huge mistake. The technicians who had to use the manual had a difficult time making sense of its instructions. They had to repeatedly ask for clarification, and one of them told me that the pure text descriptions were just too cumbersome to follow. They were fearful of using these instructions at all, knowing that a single misstep could lock the controllers into an irrecoverable state. It was a ugly situation all around.

The problem was that this programmer didn’t try to make things easy for the users. For one thing, he failed to consider that some technicians were not native English speakers, and that they might struggle with the wording. More importantly though, this programmer expected too much from his audience. He wanted to reduce these instructions to their bare essentials, thinking that would be adequate. He failed to consider that even an intelligent, otherwise careful reader might be tempted to jump over instructions, or would gloss over some critical detail. This is a common pitfall when time is short, and when the users are confronted with pages and pages of bland text.

A few carefully chosen images, with suitable captions, can go a long way toward preventing that. When I saw that the junior programmer was stripping away all the screen capture images, I cautioned him against that. “These images may not be strictly necessary,” I said, “but they help clarify a lot of details. For one thing, they show the user exactly which button to push, or which window to select. This makes the instructions much easier to understand, and reduces the likelihood of a human error.” To this day, I wish that he had heeded my warning.

Were the users intelligent enough to understand the manual, as he claimed? Certainly—but intelligence is no guarantee against human error. Could the images have been construed as talking down to the user? Perhaps—but in my experience, sophisticated users seldom respond that way. Rather, most of them seem to understand the value that these images bring to the table. Perhaps it’s because most of them know what it’s like to be frazzled and pressed for time, and how easily important details can be lost in the text.

So remember—a picture paints a thousand words, and a single screen capture can be worth more than a dozen pages of text. It’s a lesson that’s worth learning.