The term Bold Link is used in the context of search engine optimization (SEO) and usually describes a reciprocal link (mutual link exchange) that is placed on a highly authoritative and trustworthy resource.
The key element here is the significant weight or high rating of the source from which the link comes. In the past, this rating was measured by metrics such as TCI (Thematic Citation Index, used by Yandex) or PageRank (PR) (a Google metric). High values of these indicators meant that a given site was transmitting significantly more “link juice” or authority to the linked resource.
Although modern search engines no longer use publicly available metrics such as TCI or PR, the concept remains valid: A bold link is one that originates from a site with high domain authority and carries a lot of weight in ranking the landing page. Obtaining such a link, even if it is reciprocal, is considered a valuable asset for a site’s SEO profile.