Regions
A region is a geographic location where AWS has data centers. Data centers are clustered into "availability zones" (or "AZ" for acronym masochists enjoyers).
By default, your S3 bucket is replicated across multiple availability zones in a single region. That said, there are options to automatically replicate your bucket's data across multiple regions. (We won't do that, but it's good to know about.)
Which is true?