<P> A security thread is a security feature of many banknotes to protect against counterfeiting, consisting of a thin ribbon that is threaded through the note's paper . </P> <P> Usually, the ribbon runs vertically, and is "woven" into the paper, so that it at some places emerges on the front side and at the remaining places at the rear side of the paper . Usually, it is made of metal foil, but sometimes of plastic . Often, it has some text or numbers (e.g., the denomination) engraved . </P>

What is the security thread on us currency