"Link in bio" is the workaround for platforms that allow only one clickable link in a profile and few or no links inside posts. The single bio link points to a landing page that fans out to everything you want followers to reach — your shop, latest post, newsletter, booking page and more.
It matters because it is the bridge from social attention to owned destinations where you can actually convert. Since captions rarely carry live links, the bio link is often the only path from a post to a purchase or a sign-up, which makes it a critical, and measurable, piece of the funnel.
Treat the bio page like a landing page, not a link dump: lead with the current priority, keep the list short, and track taps per link so you can reorder for what converts. Update it to match your latest campaign, and use per-link data to see which content actually drives action.