A "link in bio" is a common phrase on social media platforms like Instagram, referring to a clickable hyperlink placed in a user's profile bio. This allows them to direct their followers to external websites, products, or services. Custom QR codes are a popular way to promote a "link in bio" as they can be scanned by smartphones and instantly redirect users to the desired webpage. By utilizing a "link in bio," individuals and businesses can increase traffic to their website, boost their online presence, and ultimately drive more sales.