Being known accurately for what you actually do, by the people who need to know it.
Personal branding has an unfortunate name. Stripped of the marketing vocabulary, it's the question of whether the people who make decisions about you have an accurate idea of what you're good at. You already have a reputation whether you manage it or not; it was assembled from whatever fragments happened to be visible, which is usually your most recent work and your loudest moment. The honest version of this skill is narrow: do work worth being known for, make it visible to the people for whom it's relevant, and describe it specifically enough to be memorable. The dishonest version — being known for more than you do — works briefly and fails expensively.
Posts confident, well-structured takes on a discipline they have never practised, assembled from other people's posts about it. The writing is genuinely good and the engagement is real. Has built a reputation that would collapse on contact with one specific question from anyone who does the work, which is why the strategy requires a steadily larger audience of people who don't, and can never be brought anywhere near the actual job.
Does consistently excellent work and mentions it to no one, on the principle that good work speaks for itself. It does not; it speaks to roughly four people, none of whom are in the room where the promotion is discussed. Is passed over by a colleague with a thinner record and a clearer story, and concludes that the place rewards self-promotion over substance — which is half right, and the wrong half to act on.
Describes themselves as a technology leader, builder, problem solver and lifelong learner, all of which is true and none of which distinguishes them from anyone. Has optimized the description to exclude no opportunity, and thereby produced a positioning nobody can recall an hour later or repeat to a third party, which is the only mechanism by which opportunities actually travel. Has been described in three separate conversations as "someone in tech, I think."
Builds a reputation out of proximity: the well-known employer, the client logo, the conference attended, the famous person met. Mentions each early. The credentials are entirely real and none of them describe anything the Borrowed Credibility personally did, which becomes apparent at roughly the same moment in every conversation, usually the second follow-up question. Has, in fairness, done genuinely good work somewhere in there, and has never once led with it.
You did the hardest work on a project and the write-up credits the team generically. What would you do — leave it, since it was a team effort, or add a specific line about what you personally solved?
Your job title and your actual expertise have drifted apart over three years. What would you do — keep the title as your description, or work out the one sentence that says what you're now genuinely the person to ask about?
You're asked to describe what you do at a company event. What would you do — give the broad version that keeps every door open, or the specific version that will be remembered and repeated by one person to another?