2G (or 2-G) is short for second-generation wireless telephone technology. Second generation 2G cellular telecom networks were commercially launched on the GSM standard in Finland by Radiolinja (now part of Elisa Oyj) in 1991.
Three primary benefits of 2G networks over their predecessors were that phone conversations were digitally encrypted; 2G systems were significantly more efficient on the spectrum allowing for far greater mobile phone penetration levels; and 2G introduced data services for mobile, starting with SMS text messages.
2G has been superseded by newer technologies, such as 2.5G, 2.75G, 3G, and 4G; however, 2G networks are still used in many parts of the world.
3G or 3rd Generation, is a family of standards for mobile telecommunications. Services include wide-area wireless voice telephone, video calls, and wireless data, all in a mobile environment.
3G allows simultaneous use of speech and data services and higher data rates (up to 14.0 Mbit/s on the downlink and 5.8 Mbit/s on the up-link with HSPA+). 3G offers a wide range of applications like Mobile TV,Video Conferencing,Tele-medicine,Location Based Services,Video on Demand.