Call it whatever you’d like: reputation, image, or personal brand. They all mean the same thing—they describe what you bring to the table professionally. Without that personal branding, you risk being just another face in the crowd, which is not a good position for anyone seeking advancement.
Just like many people confuse advertising and marketing, we still have lots of problem with the world personal branding as we're taught humility is a virtue. But as Dorie Clark explains, marketing is not about shamelessly selling yourself but rather "about understanding and identifying your core strengths, and then helping others understand them, as well."
The opportunity is here though: "If you’re blogging about your field of interest, or curating interesting tweets, or regularly update your LinkedIn profile and share high-quality articles you’ve read, that will rank highly in search results and present a strong professional image to the world."
You are the content you publish.