When people (almost always men) explain the product design methods in my own book to me, I say I’m well-acquainted with them, mentally roll my eyes, and move on. I hadn’t developed a succinct explanation for what distinguishes mansplaining, so I spent a few minutes drafting a diagram, as I often do to examine or explain ideas in my work. I realised the “-splaining” part comes down to three factors:

Do they want the explanation? If someone asks you a question, explain away! Unsolicited explanations may be fine (within reason) if you’re someone’s teacher or manager. Explaining after they’ve declined your help is almost always disrespectful. Conversation is a good place to start building the habit of consent.

Are you making bad assumptions about competence? Explaining things to knowledgeable people isn’t just wasting everyone’s time. You may, regardless of your intent, undermine them by implying you don’t trust their competence or intelligence. You also run the risk of undermining yourself by looking like you have an inflated opinion of your own knowledge.

How does bias affect your interpretation of the above? Both questions are complicated by sexism and other kinds of bias. We’re all taught gender bias in behavior and communication from an early age, with boys and girls being criticised and praised for different behaviors in school. We all like to think we treat people fairly, but men often assume women are less competent, and white people are likely to assume darker skin equals lower intelligence.

When yet another colleague brought up his mansplaining worries, I decided to post the diagram on Twitter, where my professional community often discusses communication issues. I was not quite prepared for the viral response—3,300 comments, 50,000 retweets, and 120,000 likes, as of Friday morning. I’ve seen stories on several blogs, and someone even translated it into Serbian.

Thousands of female-appearing Twitter users started sharing the post, asking to print it on business cards or staple it to the foreheads of men. (Some added: asking first is polite behaviour for any gender.)