Transmission Control Protocol - ensures reliable, ordered delivery of data over networks. Like registered mail that guarantees delivery and confirms receipt.
Web browsers use TCP to ensure that web pages are downloaded completely and in the correct order.
TCP is a core Internet transport protocol, not a cloud provider service. All major clouds support TCP for networking between clients, load balancers, VMs/instances, containers, and managed services (for example, TCP-based HTTPS, SSH, and database connections).