What is a "serverless" app?

The application itself should not run application-specific functionality on a server. All of its functionality should run on end-points. However, the application may use non-app-specific servers with the caveat that they must not be part of the trusted computing base. This is the case with storage systems like Amazon S3 and Dropbox, for example, because Blockstack's data is signed and verified end-to-end (so the storage systems are not trusted to serve data). Serverless can also mean applications where some amount of server-side logic is still written by the application developer but unlike traditional architectures is run in stateless compute containers that are event-triggered, ephemeral (may only last for one invocation)