"Trust seals" is another term for trust badges. If you search for "trust seals" on Google, you'll see that it comes up 68,000 times, mostly in reference to website assurances of security, fast shipping and more.
You might also notice that many website trust seals have the look of a different kind of seal: a wax seal. Below is an example downloaded from Shutterstock, but you can find thousands of others online.
Wax seals have been used for centuries to seal documents. Over time, embossed seals came to symbolize formality and authenticity in documents and correspondence.
Seals have a rich history that dates back to the civilizations of the Indus Valley and Mesopotamia. During this period, the first seals were formulated with clay. A small round cylinder, engraved with written characters, would be used to roll an impression onto the clay while it was still wet.
In the Middle Ages, wax seals came into common use among royals, bishops, and government officials to authenticate official documents. Famously, King John of England affixed a large wax seal to agree to the Magna Carta in 1215. By the latter part of the 13th century, all segments of European society were using seals, both for business purposes and personal messages such as proclamations of love. This history explains how the wax seal came to be associated with trustworthiness.
A broken seal, by contrast, meant broken trust -- someone had tampered with a document that was meant for your eyes only.
By the 20th century, the use of wax seals declined, with their primary function as part of special occasions such as wedding invitations. But the image of a wax seal remains a potent and widely recognized trust symbol to this day.