A glossary of the most common terms associated with the IWF's mission to eliminate child sexual abuse imagery online. 

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 enables 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: Images involving penetrative sexual activity; images involving sexual activity with an animal or sadism.

B: Images involving non-penetrative sexual activity.

C: Other indecent images not falling within categories A or B.

Child sexual abuse images/videos/ imagery/content/material

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.


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

Dark net

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

Gateway sites

A webpage that provides direct access to child sexual abuse material but does not itself contain it.


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

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 which are 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.

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.

Proactive/proactively searching/ proactively seeking

We can now actively search for child sexual abuse content, in addition to taking public reports. We’re one of only a few Hotlines 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.


Re-victimisation, or repeat victimisation is what happens to a victim when their image is shared online. 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.

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


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 ''


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. www.iwf. and Hotline 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.