What is the Difference between GPRS, Edge, 3G and HSDPA and 4G ?

Mobile networks are at last here and we use them every day as part of our normal business and personal lives.  However many people I talk to still get confused with the differences between them.The difference is :-
1G :- Refers to the first-generation of  wireless telephone technology mobile telecommunication .These are the analog  telecommunications standards that were introduced in the 1980s .Then came
                   2G :-  Second-generation wireless telephone technology mobile telecommunication . Second generation 2G cellular telecom networks were commercially launched on the GSM standard in Finland by Radiolinja in 1991. Three primary benefits of 2G networks over their predecessors were that phone conversations were digitally encrypted and 2G introduced data services for mobile, starting with SMS text messages.
                     Then came 2.5G (second and a half generation) gave birth to GPRS technology (General Packet Radio Service)
                   While  3G was on the way but we saw one more incremental step before this was rolled out. 2.75G (EDGE)  which provide Enhanced Data rates for GSM Evolution , EGPRS
                  Then finally came 3G 3rd generation mobile telecommunications, gave us more reliable faster data rates and better platform that allows synchronous voice and data usage.
           Currently High Speed Packet Access (HSPA) is a combination of 2 mobile technology protocol   HSDPA (High Speed Down-link Packet Access) and HSUPA (High-Speed Uplink Packet Access) is the standard for most mobile phones. released on 2008.
            and now comes 4G  Fourth Generation of mobile telecommunication which leaves the 3G to far behind.4G has the potential to be insanely fast. The various technologies should be able to deliver download speeds of 1Gbps when stationary (in the home), and 100 Mbps while mobile .Currently, advertised 4G is really just late-stage 3G. The country like USA and Japan have already been using this service. The formats designated by the International Telecommunication Union (ITU) as “true 4G technologies” are:

• LTE Advanced (Long Term Evolution Advanced)
• WiMAX