The widely used security protocol for secure online communications is Transport Layer Security (TLS). TLS encrypts data transmitted between a client and server, ensuring privacy and integrity. It protects sensitive information from interception and tampering by providing a secure communication channel over networks. E-commerce websites, banking services, and email providers commonly implement TLS to establish trust with users, safeguarding personal and financial information during online transactions. Its importance in maintaining cybersecurity cannot be overstated.