SSL inspection (also TLS inspection or HTTPS inspection) decrypts encrypted web traffic at a security gateway, inspects the content for malware and policy violations, and re-encrypts it. Without SSL inspection, threats inside encrypted traffic remain invisible. You need a trusted certificate on all clients and a high-performance gateway. Consider data-protection aspects: certain categories (banking, health) should be excluded from inspection. In your ISMS you document SSL inspection as a network-security control, including the exemption list.