Region

In Azure

A set of data centres deployed within a defined perimeter and connected through a dedicated  low-latency network. Azure has 42 Regions Available and 12 more announced as of August 2018 .

 

In AWS

A region provides multiple, physically separated and isolated Availability Zones which are connected with low latency, high throughput, and highly redundant networking. AWS provides 18 Regions with four more announced as of August 2018.

In the Google Cloud Platform (GCP)

A Geographical location that contains one or more zones.

A region is a specific geographical location where you can run your resources. Each region has one or more zones, ex:

Region: Australia-Southeast1

Where is it: Sydney, Australia

Number of Zones: 3

  1. Australia-southeast1-a
  2. Australia-southeast1-b
  3. Australia-southeast1-c

It is available in 17 Regions and 52 Zones

References:

https://aws.amazon.com/about-aws/global-infrastructure/

https://azure.microsoft.com/en-au/global-infrastructure/regions/

https://azure.microsoft.com/en-au/global-infrastructure/geographies/

https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Concepts.RegionsAndAvailabilityZones.html

https://aws.amazon.com/about-aws/global-infrastructure/

https://cloud.google.com/compute/docs/regions-zones/