where Edge computing is used and basic intro of Edge Computing , IS Edge computing is an extension of which technology ?

Before Answering  this Question (edge computing is an extension of Which technology) 

first we need to understand what is Edge computing and how it is connected to other technologies,  is this  extension of any technology or not

What is the Edge computing?

Edge computing that takes place at the edge of corporate networks, with the edge(end device) being defined as the place where end devices access the rest of the network things like phones, laptops, industrial robots, and sensors.The edge used to be a place where these devices connected so they could deliver data to, and receive instructions and download software
updates from a centrally located data centre or the cloud.

For example, 

            if sensors in valves at a petroleum refinery detect dangerously high pressure in the pipes, shutoffs need to be triggered as soon as possible.With analysis of that pressure data taking place at distant processing centres, the automatic shutoff instructions may come too late. But

with processing power placed local to the end devices, latency is less, and that roundtrip
time can be significantly reduced, potentially saving downtime, damage to property and even lives. Even with the introduction of edge devices that provide local computing and storage, there will still be a need to connect them to data centres, whether they are on premises in the cloud.

Edge devices can collect, sort and perform preliminary analysis of the data, then send it along to where it needs to go(to centralised applications or some form of long-term storage, again either on-premise or in the cloud). Because this traffic may not be time-sensitive, slower, less expensive connections possibly over the internet  can be used And because the data is pre-sorted, the volume of traffic that needs to be sent at all may be reduced.So the upside of edge computing is faster response time for applications that require it and slowing the growth of expensive long-haul connections to processing and storage centres.

So from the above explanation the Edge computing is neither a extension of any Technology nor synonym of IOT(Internet if things),it not even going to Replace the cloud computing all are different technologies are working together  to optimize the work and get effective results.
in the clouding storage the data is stored in remote desktop connected over HTTP protocol, in Edge computing the data is data in local device like in mobile, inbuilt memory card in the machine like that.