Before advancing, it should be known that 1G, 2G, 3G, 4G, 5G etc refers to the different generations of wireless communication technology characterized by having a defined range of speed.
GPRS(General Packet Radio Service)
GPRS is a packet-based* wireless communication service. It is a 2G technology network that support a download speed of up to 114Kbps. Limitation of GPRS is that GPRS data cannot be sent while a voice call is in progress.
EDGE(Enhanced Data GSM Evolution)
GPRS and EDGE are both 2G technology but EDGE is significantly faster with a download speed of up to 384Kbps. EDGE is sometimes called a 2.5G network as it also has some characteristics of a 3G network but it doesn't satisfy the specification.
Introduction of 3G network made video calling and seamless streaming of video possible, with download speed of up to 3.1Mbps.
HSDPA(High-Speed Down-link Packet Access)
It is based on the 3G network and an enhancement to 3G. Thus has a, faster speed, download speed can be up to 14Mbps. HSDPA is sometimes called 3.5G.
HSPA+(Evolved High-speed Packet Access) HSPA+ is an evolution HSPA(HSDPA&HSUPA)
It is a 4G technology that allows download at a rate of up to 168Mbps.
4G LTE(Long Term Evolution)
LTE is a 4G communication standard that supports HD video streaming, download speed as high as 299.6Mbps.