ISP (internet service provider) describes a business that provides users with access to the internet and related connectivity services, such as broadband, mobile data, hosting, email and cloud infrastructure. In legal practice, ISPs are central to disputes and regulatory issues involving online content, data protection, interception, cybersecurity, e‑commerce and consumer protection.The term is used descriptively across the UK and Ireland, but is reflected in legislation and case law. In the UK, relevant provisions and concepts appear in the Communications Act 2003, the Investigatory Powers Act 2016, the Online Safety Act 2023 and retained EU e‑commerce rules. In Ireland, ISPs are addressed in legislation including the Communications Regulation Acts, the ePrivacy regime and the implementation of the EU eCommerce and Digital Services legislation.Key issues for ISPs include liability for third‑party content, notice-and-takedown procedures, data retention and disclosure to law enforcement, lawful interception, network neutrality, and regulatory obligations imposed by Ofcom (UK) and ComReg (Ireland). Usage of the term and its core legal implications is broadly consistent across England & Wales, Scotland, Northern Ireland and Ireland, though specific regulatory frameworks and enforcement bodies differ.