The Global System for Mobile Communications (GSM) is a standard developed to ensure mobile phone networks can communicate effectively. It was first introduced in the 1980s and has since become the most widely used mobile communication technology worldwide. GSM allows for voice calls, text messaging, and data services, enabling users to connect seamlessly across different regions. GSM operates on various frequency bands and uses digital technology to improve call quality and security. It also supports features like roaming, which allows users to access their mobile services while traveling abroad. Overall, GSM has played a crucial role in the evolution of mobile telecommunications.