Illegal vs harmful content
Illegal content breaks UK law (for example, child sexual abuse imagery or incitement to terrorism). Harmful content is legal but can damage a child, such as some self-harm or pro-eating-disorder material.
In plain English
Illegal content breaks UK law (for example, child sexual abuse imagery or incitement to terrorism). Harmful content is legal but can damage a child, such as some self-harm or pro-eating-disorder material.
Why it matters
The Online Safety Act gives platforms different duties for each. Illegal content must be removed quickly. For content harmful to children, platforms must use age assurance and risk assessments. Knowing the difference helps families understand what they can expect to be removed.
Sources
This is practical educational content to support families. For case-specific concerns about a child's safety, contact the NSPCC helpline on 0808 800 5000 or your local safeguarding team.
Last reviewed: 2026-05-17