KCSiE stands for Keeping Children Safe in Education, which is mandatory statutory guidance from the UK's Department for Education (DfE) for all schools and colleges in England, outlining their legal duties to protect and promote the welfare of children under 18, covering everything from online safety and abuse prevention to staff training and managing safeguarding concerns. It sets out "must" (legal) and "should" (best practice) actions, with annual updates to reflect new challenges like AI, and is crucial for ensuring a safe learning environment.