A modern smartphone is not just in the cellular network, but through it connected to the Internet. It is about the existence of such a connection and say these mysterious letters. Each of them signifies a specific data transmission rate. That is why in different parts of the city and even the building they can be changed, as changing the maximum speed of your Internet connection.
G is the slowest for today speed networks of the second generation, 2G. Indicated by GPRS, and is around 171.2 kbps.
E is Edge GPRS. It is more than two times higher than the previous and is 474 kbps.
3G is the network speed of the third generation. It is already possible to comfortably watch streaming video is not the highest resolution. The speed is around 3.6 Mbps.
H or 3G+ is a network of the third generation. The speed is about 7-8 Mbps. Video is becoming to look more and more comfortable, you can download quite large files.
H+ is an improved version of HSDPA speeds up to 42 Mbit/s, in practice about 20 Mbps.
LTE is the most modern version of the fourth generation networks. For moving objects, the speed should theoretically be around 100 Mbps.
All of the speed is very conditional. Each operator in your area, the speed may be materially different from those stated. So just be guided by the principle: the bigger the letter, the higher the speed. But there are exceptions. So, the speed of H in unstable signal may be less comfortable than slow but reliable E. So that when an unstable connection can be a useful translation device to use 2G networks. The item is, for example, in setting up of Android smartphones.