The “G” in wireless networks refers to the “generation” of the underlying wireless network technology.
Description of each generation:
Cell phones began with 1G in the 1980s. 1G is an analog technology and the phones generally had poor voice quality, and would sometimes experience dropped calls. The phones used for 1G were extremely large (compared to today’s cell phones) and the term “bag phones” is sometimes used to describe them.
The 2G telephone technology introduced call and text encryption, plus data services like SMS and MMS. 2G was introduced in 1991 in Finland and the main difference between 1G and 2G, is that the radio signals used by 1G network are analog, while 2G networks are digital.
3G networks were introduced in 1998. 3G has faster data-transmission speeds so you could use your cell phone in more data-demanding ways like video calling and mobile internet.
The fourth generation of networks is called 4G, which was released in 2008. It supports mobile web access like 3G but also gaming services, video conferencing and generally things that demand higher speeds.
5G is a generation currently under development. It denotes the next major phase of mobile telecommunications standards.