Phone human-readable description of the message we trying to accomplish. Search human-readable description of the message we trying to accomplish. Map pin human-readable description of the message we trying to accomplish.

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Banner site

A website or webpage made up of adverts for other websites with text links or images that take you to third-party websites when you click on them.


A blog is a discussion or information site made up of separate entries, or posts. Most are interactive, and visitors can leave comments and even message each other on the blog. The interactivity is what makes them different from other static websites.


The Child Abuse Image Database (CAID) is a project led by the Home Office which will enable UK law enforcement to assess, categorise and generate unique hashes for tens of millions of child abuse images and videos found during their investigations.

Category A, B and C

We assess child sexual abuse images and videos based on UK law, according to the levels in the Sentencing Council's Sexual Offences Definitive Guidelines. Since April 2014, there have been three levels: A, B and C. You can see what they mean in the chart below.
A Images involving penetrative sexual activity; images involving sexual activity with an animal or sadism. We describe this category as “rape and sexual torture”.
B Images involving non-penetrative sexual activity.
C Other indecent images not falling within category A or B.











Child sexual abuse images/ videos/ imagery/ content

Images or videos that show the sexual abuse of children. We use the term ‘child sexual abuse’ images to reflect the gravity of the images we deal with.

Criminally obscene adult content

Images and videos that show extreme sexual activity that’s criminal in the UK.


These are file hosting services, cloud storage services or online file storage providers. They are internet hosting services specifically designed to host users’ files.

Dark web

The Dark web, also known as the Dark net, is the hidden part of the internet accessed using Tor. Tor is anonymity software that makes it difficult to trace the users’ online activity.

Disguised websites

Websites which, when loaded directly into a browser, show legal content - but when accessed through a particular pathway (or referrer website) show illegal content, for example child sexual abuse images.

Domain alerts

Details of domain names that are known to be hosting child sexual abuse content.


Also known as a ‘message board’, a forum is an online chat site where people talk or upload files in the form of posts. A forum can hold sub-forums, and each of these could have several topics. Within a topic, each new discussion started is called a thread, and any forum user can reply to this thread.

Hash/ Hashes

A ‘hash’ is a unique code, or string of text and numbers generated from the binary data of a picture. Hashes can automatically identify known child sexual abuse images without needing to examine each image individually. This can help to prevent online distribution of this content.

Hidden services

These are websites that are hosted within a proxy network, so their location can’t be traced.

Image board

An image board is a type of internet forum that operates mostly through posting images. They’re used for discussions on a variety of topics, and are similar to bulletin board systems, but with a focus on images.

Image host/ Image hosting site

An image hosting service lets users upload images and they’re then available through a unique URL. This URL can be used to make online links, or be embedded in other websites, forums and social networking sites.

Image store

A collection of images stored for non-commercial purposes. An example would be a hidden folder in an otherwise innocent website.

IWF Reporting Portal

A world-class reporting solution for child sexual abuse content, for countries which don’t have an existing hotline.


A list of terms associated with child sexual abuse material searches.


Internet discussion groups dedicated to a variety of subjects. Users make posts to a newsgroup and others can see them and comment. Sometimes called ‘Usenet’, newsgroups were the original online forums and a precursor to the World Wide Web.

Non-photographic child sexual abuse content

Images and videos of child sexual abuse which aren’t photographs, for example computer-generated images.

Onion sites

Onion sites get their name from the vegetable, which is made-up of lots of different layers. Like onions, onion sites sit behind layers and layers of anonymity which make them, and the people using them, very difficult to trace.

Proactive/ proactively searching/ proactively seeking

We can now actively search for child sexual abuse content, in addition to taking public reports. We’re the only hotline in the world that can do this. 

Proxy network

These are systems that enable online anonymity, accelerate service requests, encryption, security and lots of other features. Some proxy software, such as Tor, attempts to conceal the true location of services.


These webpages are set up to redirect the user to another hosted webpage. When a redirector URL is browsed, the user request is automatically forwarded to the destination URL. Sometimes, when the redirector webpage is loaded in the browser it hides the destination URL.


Re-victimisation, or repeat victimisation is what happens to a victim when their image is shared more than once. A single image of a victim can be shared hundreds or thousands of times.

Service Provider/ Internet Service Provider

An internet service provider (ISP) is a company or organisation that provides access to the internet, internet connectivity and other related services, like hosting websites.


This is the process where a company that uses our IWF URL List tests their system every quarter to check they’re using it properly.

Social networking site

A social networking service is a platform to build social relations. It usually has a representation of each user (often a profile), their social links and a variety of other services. Popular examples include Facebook and Twitter.

Top-level domain (TLD)

Domains at the top of the domain name hierarchy. For example .com, .org and .info are all examples of generic top-level domains (gTLDs). The term also covers country code top-level domains (ccTLDs) like .uk for UK or .us for US and sponsored top-level domains (sTLDs) like .mobi or .xxx


This is an acronym for Uniform Resource Locator. A URL is the specific location where a file is saved online. For example, the URL of the IWF logo which appears on the webpage is

Web archive

This is a service which makes it possible to view historic copies of websites, which are periodically archived over time.


A document which can be seen using a web browser. A single webpage can hold lots of images, text, videos or hyperlinks and many websites will have lots of webpages. and are both examples of webpages.


A website is a set of related webpages typically served from a single web domain. Most websites have several webpages.

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