Set the Region

Aug 2017

Regions, or as they are correctly know, Availability Zones (AZs) define where your EC2 Instance is created. Generally you want the EC2 Instance to be created close to where it will be used, so either in an AZ close to you or in an AZ close to the customer(s).
Here is a list of AZ names (August 2017) bear in mind that these can (and probably) will be changed, deprecated or added to by Amazon as time goes on.

Code Name
us-east-1 US East (N. Virginia)
us-east-2 US East (Ohio)
us-west-1 US West (N. California)
us-west-2 US West (Oregon)
ca-central-1 Canada (Central)
eu-west-1 EU (Ireland)
eu-central-1 EU (Frankfurt)
eu-west-2 EU (London)
ap-northeast-1 Asia Pacific (Tokyo)
ap-northeast-2 Asia Pacific (Seoul)
ap-southeast-1 Asia Pacific (Singapore)
ap-southeast-2 Asia Pacific (Sydney)
ap-south-1 Asia Pacific (Mumbai)
sa-east-1 South America (São Paulo)

In my example I am going to use the Availability Zone in London, so my region = “eu-west-2”
Please bear in mind that most Availability Zones have two or more Zones. So London has “eu-west-2a” and “eu-west-2b”. You cannot specify which one to use, you will just get an error, you must always use the AZ without the a,b,c suffix.