URL blocking FAQs

What is the IWF URL List?

The IWF list contains specific web pages, or URLs. Every URL on the list depicts indecent images of children, advertisements for or links to such content, on a publicly available website. The list typically contains 6,000 URLs at any one time and is subject to fluctuation. The list is updated twice a day to ensure all entries are still live at the time of review.

Any child sexual abuse content actioned on a UK website is typically removed within hours so this content is not added to the list. Details of any child sexual abuse content hosted outside the UK are passed to Hotline in that country so they can investigate it within their own legislation and with their national law enforcement agencies. Whilst processes to have the content removed are instigated, the specific URLs are added to a list which we make available to service providers, under licence, so they can develop technical solutions to prevent their users being accidentally exposed to it.

We have no plans to extend the type of content included on the child sexual abuse material list.

What is a URL?

URL stands for Uniform Resource Locator. It is an internet address (for example, https://www.iwf.org.uk/report), usually consisting of the access protocol (e.g. https), the domain name (e.g. www.iwf.org.uk), and optionally, the path to a file or resource residing on that server (e.g. report). The URLs contained in the IWF list are all for individual webpages with child sexual abuse content. A whole website will only be included on the list if that whole domain is dedicated to the sale or distribution of child sexual abuse images or provides direct active links to such content from the site domain page level.

What are the criteria for a URL to be added to the list?

The URLs are assessed according to UK law, specifically the Protection of Children Act 1978, and in accordance with the UK Sentencing Guidelines Council. All URLs added to the list depict indecent images of children, advertisements for or links to such content. This content is likely to be an offence to view, download, distribute, or possess in the UK. This includes pay-to-view websites as well as sites where child sexual abuse images are swapped, traded or posted. The policy by which a decision is made to include a URL on the list can be seen here.

Are the images definitely criminal?

We refer to content as potentially criminal because a definitive legal judgement is a matter for the Courts.

What is blocking?

Many companies in the internet industry, including internet service providers, mobile operators, search providers, and filtering companies use the IWF list on a voluntary basis to protect their customers from accidental access to child sexual abuse content. The companies' blocking solutions may be different and may be applied across all or some of their services and technology platforms. Our role is restricted to the compilation and provision of a list: the blocking solution is entirely a matter for the company deploying it. Any decision to convert or adapt the list to block whole domains may lead to the over-blocking of legitimate content and is not supported by the IWF.

Which laws are relevant?

The Protection of Children Act 1978 as amended in the Sexual Offences Act 2003, makes it an offence to take, make, permit to be taken, distribute, show, possess with intent to distribute, or advertise indecent photographs or pseudo-photographs of children under the age of 18. The ‘making’ of such images includes downloading, that is, making a copy of a child sexual abuse image on a computer, so, in the UK, accessing such content online is a serious criminal offence, attracting a possible term of imprisonment up to 10 years.

What is the Government's position regarding blocking?

Home Office Ministers have spoken widely on the Government's positions and expectations regarding the blocking of online child sexual abuse content since 2006.

For more information see laws relevant to the IWF’s work

Who assesses these images and how are they trained?

The reports received via the IWF internet 'Hotline' are assessed by Internet Content Analysts (ICAs) who have comprehensive, up-to-date, and in-depth training on relevant UK legislation and image assessment with the appropriate UK police personnel. The IWF carefully vet their ICAs and carry out Police and Criminal Records Bureau searches on them. The policy by which a decision is made to include a URL on the list can be accessed here.

Who oversees the operations of the IWF? Who 'regulates' the IWF?

IWF policies are subject to approval by the IWF's Board of Trustees and Funding Council. The policy by which a decision is made to include a URL on the list can be accessed here. The systems and processes for managing the URLs that are added to our list are comprehensively inspected and audited by independent external examiners.

Who is entitled to have access to the list of potentially criminal URLs?

IWF subscribing members and Licensees are entitled to secure access to the list subject to legally binding license agreements, as are law enforcement agencies and associated Hotlines who are members of INHOPE on a reciprocal basis for non-commercial use.

Who are the IWF Members?

For a full list of members, please see: IWF Members. 

How is the list kept secure and confidential?

We take all reasonable steps to ensure the security of the list data. It's provision is subject to legally binding licence agreements and it is supplied to licensed companies over a secure interface.

The IWF grants a non-transferable licence to use the list for licensed use only. The Licensee must ensure that any employees who need to access the list comply with terms agreed. The Licensee agrees not to, at any time, produce, publish, sell, let, lend or otherwise disclose the list. The Licensee is also obliged to keep the list confidential and secure.

The systems and processes used to compile this list are inspected by independent professionals and are validated as being consistent with best practice.

What happens once a child sexual abuse URL has been identified?

It is traced to an apparent country of origin. If it is hosted in the UK then we work in partnership with the National Crime Agency and the hosting provider to ensure the content is removed quickly. If the content is hosted abroad then we pass that information to the relevant hotline or law enforcement agency in that country so the website can be investigated by the relevant national law enforcement authorities and removed. We also add Non-UK hosted URLs to the IWF URL list of child sexual abuse content so that the industry can block access to them whilst steps are being taken to have that content removed.

Are site 'owners' notified that they have been added to the list?

Notifying the website owner and or hosting provider of any blocked URL is the responsibility of the hotline or relevant law enforcement agency in the country believed to be hosting the content. However, any party with a legitimate association (#1)  with the content or a potential victim or the victim’s representative, hosting company, publisher or internet consumer who believes they are being prevented from accessing legal content may appeal against the accuracy of an assessment. We would only remove a URL after due consideration of all the facts. Any URLs on the list which are no longer live or no longer contain potentially criminal child sexual abuse content or links to such, are removed from the list on a daily basis. 

(#1) A party affected by the issue of a notice or blocked by the addition of a URL to the IWF URL List

What does it mean if an organisation or company is supplied with the list?

The organisation or companies supplied with the IWF URL list may receive the list directly by virtue of their membership or through being a subsidiary or customer of a company being supplied directly with the list or through an affiliation with a member body.

How do organisations or companies implement the list?

IWF members come from a wide variety of backgrounds and therefore their use and implementation of the list is also varied. There is no “one size fits all approach”.

What is an 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 (e.g. hosting websites).

What is a search engine or search provider?

Search engines provide web-based technology to enable the user to search the internet for information. Providers use technology to crawl the web and index websites. The search engine is an interface which allows an internet user to enter a word or words into a search box in order to interrogate the index and return results on the subject they are interested in. Search engines can be accessed via computer, mobile phone, games consoles, television, wireless devices and other handheld devices with access to the internet.

What is a mobile operator?

A mobile network operator, also known as wireless service provider, wireless carrier, mobile phone operator or cellular company, is a telephone company that provides access and services for mobile phone subscribers.

What is a filtering company?

A filtering company provides products or services which facilitate the filtering of internet content, for example, to stop adult content being seen by minors in the UK. Filtering companies making use of the IWF list are trying to ensure that those who use their filtering products will be protected from inadvertently accessing websites with child sexual abuse content.

How do I know if I am protected?

If you want to confirm whether or not your ISP is already blocking or filtering URLs on the IWF list or if you have any questions, please contact them directly.

What else can I do to protect my family from accessing potentially inappropriate online content?

There are a number of filtering products which can further protect internet users from accessing criminal and/or inappropriate online content. 

Does this stop even the most determined people from looking at online child sexual abuse images?

This initiative is one element in a wider effort to combat the making and distribution of images of child sexual abuse via the internet and the activities of determined criminals who exploit internet-based technologies and services to this end. This effort involves a partnership between law enforcement, children’s services, major children’s charities, the judicial system and the UK internet industry. 

Blocking is designed to protect people from inadvertent access to potentially criminal images of child sexual abuse. No known technology is capable of effectively denying determined criminals who are actively seeking such material; only removal of the content at source can achieve that goal.