Frontend, Backend and Middleware.
KVM for EC2 virtualization
Varies a lot, C and C++, Java
Some AWS services are built on top of other AWS services. Of course, some of them are completely independent of other AWS services.
Wow .such meta...much wow
AWS is a wrapper around open source projects.
Hyper-V
Oracle / OCI
Lots and lots of perl
Not for AWS, that’s only on retail side