| Child Abuse Image Database (CAID) | A single secure database of illegal images of children. |
| Classifier | A computer programme that learns from data given to it, to then identify similar data. |
| Cloud | A network of remote servers hosted on the internet to store, manage and process data. |
| Criminal justice system | The system which investigates, prosecutes, sentences and monitors individuals who are suspected or convicted of committing a criminal offence. This also encompasses institutions responsible for imprisonment, probation and sentences served in the community. |
| CyberTipline | An online tool which enables the public and industry to report indecent images of children and incidents of grooming and child sex-trafficking found on the internet. |
| Dark web (or dark net) | Part of the world wide web that is only accessible by means of specialist software and cannot be accessed through well-known search engines. |
| Encryption | The process of converting information or data into a code that makes it unreadable to unauthorised parties. |
| End-to-end encryption | Where the content of the communication can only be seen by the sender and recipient, and not by any others – including the providers of the platforms themselves. |
| First-generation imagery | A child sexual abuse image taken by an adult that has not previously been recorded by law enforcement or industry as indecent. |
| Freedom of information requests | Under the Freedom of Information Act 2000, members of the public may request information from public authorities. |
| Geolocation | The process of identifying the location where the internet is being accessed, whether on a computer or a mobile device. |
| Green Paper | A consultation document that sets out the government’s proposals for future policy or legislation. |
| Grooming | The process by which a perpetrator communicates with a child with the intention of committing sexual abuse or exploitation. Includes forcing, manipulating or enticing a child to engage in sexual activity, either with themselves or with other children. |
| Hash | A unique digital signature of an image. |
| Indecent images of children | A photograph or pseudo-photograph of a child under the age of 18 that is deemed to be indecent. |
| Industry | Includes internet service providers (ISPs); communication service providers (CSPs) such as BT; software companies such as Microsoft; social media platforms such as Facebook; providers of search engines such as Google; and providers of email and messaging services and cloud storage such as Apple. |
| INHOPE | A foundation that develops national hotlines to help deal with child sexual abuse material online. |
| Internet protocol (IP) address | A number assigned to a device connected to a computer network. |
| Internet Watch Foundation (IWF) | An independent, not-for-profit organisation which aims to remove child sexual abuse images and videos from the internet and to minimise the availability of such material. |
| Known images | An image of a child that law enforcement and/or industry has identified as an indecent image. |
| Law enforcement agencies | Statutory agencies with responsibility for policing and intelligence, including police forces, the intelligence services and the National Crime Agency. |
| Live streaming of child sexual abuse | The broadcasting of real-time, live footage of a child being sexually abused over the internet. |
| National Security Council | A weekly forum in which government ministers meet to discuss national security. The meeting is chaired by the Prime Minister. |
| Personal data | Information that relates to an identified or identifiable individual. |
| PhotoDNA | Technology developed by Microsoft which assists in finding and removing known images of child sexual abuse on the internet. |
| Project Arachnid | A web crawler designed to discover child sexual abuse material on sites that had previously been reported to the Canadian CyberTipline as hosting such material. |
| Pseudo-photograph | An image, often created on a computer, which looks like a real photograph. |
| Rapid Evidence Assessment (REA) | A review which gives an overview of the amount and quality of evidence on a particular topic as comprehensively as possible within a set timetable. |
| Self-generated imagery | A naked or partially naked image of a child taken by the child him or herself. |
| Trusted flaggers | Individuals, governmental agencies and non-governmental organisations that are particularly effective at notifying YouTube of content that violates its Community Guidelines. |
| Uniform resource locator (URL) | The network identification or address where a particular page or resource (eg images, sound files) can be found on the world wide web. |
| Unknown images | An image of a child that has not previously been recorded by law enforcement or industry to be an indecent image of a child. |
| US | United States of America. |
| Web crawler | A computer programme that automatically searches for documents, or in this case for indecent images, on the web. |
| White Paper | A document that sets out the government’s proposals for future legislation. |