1. 1G technology, developed in the 1980s, was based on analog systems with speeds up to 2.4 kbps. It allowed basic voice calls but had poor voice quality, battery life, and size.
2. 2G technology, developed in the late 1980s-1990s, was based on digital systems with speeds up to 64 kbps. It provided clearer digital voice and SMS but required strong signals and could not handle more complex data like videos.
3. 3G technology, developed from the late 1990s to present, had transmission speeds from 125 kbps to 2 Mbps and allowed services like video calls, email, banking, and games but was expensive to build and required high bandwidth