2G, or second generation, refers to the mobile telecommunications technology that introduced digital voice services and basic data services like SMS. It improved call quality and security compared to its predecessor, 1G, which was analog. 3G, or third generation, brought faster data speeds, enabling mobile internet access, video calls, and multimedia services. It allowed users to browse the web and stream content more efficiently. 4G, or fourth generation, further enhanced these capabilities with even higher speeds and better connectivity, supporting high-definition video streaming and advanced applications like VoIP and online gaming.