The chapter addressed what smartphones, mobile applications, programming languages, and mobile operating systems are. The development, implementation, and results obtained from mobile applications in the following areas are discussed in detail: educational platforms, citizen participation with the government, teaching the pronunciation of the English language, and citizen participation in public security. Android, being the main operating system for smartphones, is the most suitable for the development of mobile applications since it guarantees that it will have the greatest possible visibility and reach, not only for its popularity but for its presence in many devices other than cell phones and its “open system” feature so that everyone who wants it can develop compatible software.