ANSWER

Before we jump into the comparison of on-premise vs. cloud vs. fog vs. edge computing we need to take a step back and use first principles thinking by first defining the terms in a stepwise manner.

Let’s start with what is computing?  For our purposes, let’s keep it simple: it’s the activity or process performed by computing devices (hardware or software) in order to achieve a specific goal or objective. The types of computations very drastically but can include activities such as retrieving data, performing searches, executing algorithms, or making decisions.

The key difference between on-premise vs. cloud vs. fog vs. edge computing has to do with where the computing takes place.

• On-Premise Computing - on-premise or “on-prem” computing generally refers to computing which takes place on resources (servers/hardware) which are located in an organization’s own facilities and data centers aka on the organization’s premises.  On-premise computing tends to be the closest to those within the organization and under the most control of the organization.

• Cloud Computing - cloud computing generally refers to computing which takes place on resources (servers/hardware) outside of an organization’s premises and which tend to be under some level of control by the organization but not as much control as on-prem.  For example, a company may run its software on the Amazon Web Services platform which runs on Amazon’s computers with the organization having control of what software to run, when to run it but not having control over exactly which hardware/server it is running on.  If the cloud infrastructure has an outage, the organization is at the mercy of the cloud provider’s ability to restore functionality.

• Fog Computing - fog computing refers to an intermediate layer or layers which are closer to the ultimate devices or consumers the organization is trying to reach.  Fog computing consists of multiple nodes which creates a decentralized network or ecosystem which is able to deliver the computation power closer to the customer.  The fog layer tends to be used for storage of less sensitive data or for computations which need to be fast without the latency involved with sending the data to a centralized computing processing center.  Consider a company which operates a number of wind farms and needs to constantly monitor and adjust the direction and angles of the wind turbines.  The further away from the wind-farm the decision is made, the higher the likelihood of  wind conditions changing before the turbine adjustments are made.  If each wind-farm had its own ability to make these determinations, these would be an example of fog computing - away from the company’s cloud or on-premise servers.

• Edge Computing - edge computing refers to computing which occurs furthest away from the organization’s premises and closes to the client’s device and possibly on the client’s device.  A familiar example of edge commuting would be a mobile app which runs on a user’s smartphone.  And if we go back to the wind-farm example, computing which takes place using hardware and software embedded in a given wind-turbine would be an example of edge computing.  Broad and less time sensitive decisions can be made in the cloud or on-premise, more time sensitive and finer-grained decisions can be made using fog-computing (ex: account for differences in weather at different wind farms), while near-instant decisions can be made using edge-computing allowing wind-turbines to make quick decisions to prevent damage in case of sudden wind gusts or to make micro-adjustments increasing the efficiency of the turbine.

Visual Example: On-Premise vs. Cloud vs. Fog vs. Edge computing?

Key Differences: On-Premise vs. Cloud vs. Fog vs. Edge computing?