Glossary

A biometric subject’s manner of walking.

An analytical method combining gas chromatography and mass spectrometry to identify different substances within a test sample. Used in fuel integrity programmes.

A subset of artificial intelligence that focuses on creating new content, such as text, images, audio, or video, by learning patterns from existing data. Common examples include language models like GPT (which powers ChatGPT) or image generation models like DALL-E. Unlike agentic AI, generative AI operates under user prompts and can’t perform tasks on its own initiative.

The identification of the geographic location of an object.

A secondary portrait image of a document holder created by laser perforation and visible in transmitted light.

An artificial watermark printed on the back of a sheet that will not appear on a scanned or copied document.

A GS1 standard number unique to each stock-keeping unit (SKU) or specific product type, but not unique to a product at unit level.

A single layer of carbon atoms arranged in a hexagonal lattice structure, forming a 2D material with exceptional mechanical, electrical, and thermal properties. It is widely studied for its potential use in fields such as electronics, energy storage, and biomedicine. Graphene is not only the thinnest, but also one of the strongest materials; it conducts heat better than all other materials; it is an excellent conductor of electricity; it is optically transparent, yet so dense that it is impermeable to gases.

An array of parallel lines with spacing comparable to wavelengths of light. The array has the ability to split white light into a rainbow because the different wavelengths are bent, or diffracted, by different amounts. Such gratings were originally produced by using a diamond to rule closely spaced lines onto glass, but they are now more often produced by optical interference.

A type of intaglio printing process, which involves engraving an image onto a cylinder. Like offset printing and flexography, gravure uses a rotary printing press.

A printing technique that uses varying shades of gray to produce an image. Unlike full colour images created by combining different colours of ink, grayscale images are produced solely from black ink.

A not-for-profit organisation that develops and maintains global standards for identifying products, associations, services and localisations and for exchanging data. The best known of these standards is the barcode, a symbol printed on products that can be scanned electronically and that is widely used in supply chains around the world.

A 1D (linear) alphanumeric barcode for labelling outer packaging and logistics units, such as pallets. Can hold more information than EAN-13 codes.

A printed security feature composed of geometric, complex patterns of interlaced or interwoven curved fine lines that are difficult to reproduce using digital print or photocopiers.

A variety of clear window, with one side of the banknote opacified.

The number of non-corresponding digits in a string of binary digits, used to measure dissimilarity. Hamming distances are used in many Daugman iris recognition algorithms.

A method of lamination whereby heat is used to transfer print from one substrate to another. Most US cigarette tax stamps are applied by this method.

The refractive index of a material is a dimensionless number that describes how fast light travels through the material. In situations where a transparent hologram is required, for instance as a laminate to cover the variable data of a passport or other ID document, instead of coating the holographic image with a metallic film, a transparent coating is made using a material with a high refractive index. The HRI materials used in this process are typically oxides (eg. titanium dioxide) or sulphides (eg. zinc sulphide). In this way, the light diffracted by the hologram can be seen, as can the variable data underneath.

Flexible woven fabric used to attach a polycarbonate biodata card to a booklet ID document, fused into the polycarbonate body of the biodata card.

The term ‘hologram’ is derived from two Greek words: ‘holos’ meaning whole or complete and ‘graphos’ meaning an image. The term therefore describes a recorded image which is complete, in that it shows, through the diffraction of light, the whole volumetric space of the image – with depth, colour and movement. This is in contrast to a conventional picture, painting or photograph which displays an object from a single viewpoint only.

An optical device that uses diffraction to shape a wavefront, as opposed to a refractive optical element (using materials with differing refractive indexes) that depends on refraction.

A method of transferring a foil from a polyester carrier to paper or other substrate through the combination of heat and pressure. Hot foil stamping can be used to support holographic anda other optically variable images which can be transferred, using heat and pressure, onto another substrate such as paper or plastic. The layers containing the image are extremely thin, typically 5-6 microns. Therefore, they need to be supported on a thicker material such as 19-micron thick polyester. The action of stamping the foil with a heated die causes a ‘release’ layer between the image and polyester support to melt, while simultaneously softening an adhesive ‘size’ coating. These combined effects allow the image to leave the polyester support and adhere to its new location.

An adhesive that is solid at room temperature and becomes liquid when heated. Used to bond two surfaces when cool.

A substrate that is a mixture of natural fibres (cotton) and plastic material, without one predominating the other.

A technique that collects and processes information from across the electromagnetic spectrum. The goal of hyperspectral imaging is to obtain the spectrum for each pixel in an image, with the purpose of finding objects, identifying materials, or detecting processes.

A set of attributes that uniquely describe a person.

A physical identity credential.

An interconnected set of identification systems – including databases, credentials, laws, processes and protocols.

A government agency or private corporation that issues and manages identities, credentials, and authentication processes.

The production, distribution or sale of counterfeit, adulterated or diverted goods via illegal and unregulated channels. Also includes the evasion of taxes on legally produced goods.

A multidisciplinary field concerned with the generation, collection, duplication, analysis, modification, and visualisation of images.

A biochemical test measuring the presence or concentration of a molecule in an extracted substrate using an antibody or antigen.

Blockchain is immutable and transparent. When data is recorded on the blockchain network, it becomes visible to other participants and cannot be changed. All blocks are connected to each other. No-one can delete, edit, revise, rewrite, update or undo, any of the blocks.

The light that emanates from a defined light source, such as the sun or a lightbulb, and illuminates an object.

Signs, indications, tokens or distinguishing marks.

An aluminium foil or paper seal bonded over the opening of usually bottles after they have been filled with pills or capsules. Provides tamper evidence but can potentially be illegally replaced if plain foils with no security features are used on the original product.

Also called the Fourth Industrial Revolution. The next phase in the digitisation of the manufacturing sector, driven by the rise of data and connectivity, analytics, human-machine interaction, and improvements in robotics.

The part of the electromagnetic spectrum between 700nm and 1.0mm wavelength. IR light lies immediately beyond red visible light and is therefore invisible to the naked eye. IR light is used in detectors and special equipment to detect security features of banknotes and other documents.

A technique that projects tiny droplets of ink directly onto a substrate, which then penetrates the surface. As there is no printing plate, the technique is favoured for printing variable and personalised data.

A banknote that is stained with a special wash-resistant ink, triggered by an anti-theft mechanism located in a cash container or security case locked with a special seal and security key. See also Intelligent banknote neutralisation system.

An optical detection system capable of determining the presence of intaglio printing on a banknote.

A security printing process that is synonymous with banknote printing but also used on ID documents and some tax stamps. The area of the image to be printed is recessed into the surface of the printing plate via engraving or etching and the recessed areas filled with high-viscosity ink. The excess ink is wiped from the plates and heavy pressure is applied to transfer the ink to the paper. The resulting raised ink profile gives intaglio-printed documents their characteristic tactility.

The fundamental building block of all modern electronic devices. An integrated system of multiple miniaturised and interconnected components embedded into a thin substrate of semiconductor material (usually silicon crystal). Also known as a chip or microchip.

A category of property that includes intangible creations of the human intellect. There are many types of intellectual property, and some countries recognise more than others. The best-known types are patents, copyrights, trademarks, and trade secrets.

An anti-theft mechanism located in a cash container or security case that is locked with a special seal and a security key. If the security case is stolen, any attempt to open it by force (or without using the correct key) will automatically trigger the mechanism and the banknotes will immediately become recognisable as stolen and should therefore be rejected at any financial institution.

The result of the interaction between two superposing waves. Interference pigment flakes are used in colour-shifting inks, and interference foils with colour-shifting properties also exist.

A security thread containing an invisible code printed in magnetic ink, which can be used to authenticate and/or denominate banknotes in sorting machines.

A specialised agency of the United Nations responsible for establishing goals and objectives of traveller identification management.

An independent, non-governmental international organisation with a membership of 165 national standards bodies. Through its members, ISO brings together experts to share knowledge and develop voluntary, consensus-based, market-relevant international standards that support innovation and provide solutions to global challenges.

A network of physical objects that are embedded with sensors, software, and other technologies for the purpose of connecting and exchanging data with other devices and systems over the internet.