Molecular or microscopic particles that can be organic or inorganic in composition and exhibit specific and unique physical, biological, chemical or spectroscopic properties. Added in very low concentration to substrates or ink as a covert authentication feature. Also...

Tamper evidence

Devices such as seals and closures that demonstrate that the product or packaging has been opened or otherwise accessed.

Tax stamp

A label or tag applied to an item that denotes that tax or excise duty has been paid on the item.