[norman784]

Basically Wasm is a virtual machine, is is very similar to JVM that is portable, but the key difference is that Wasm does not have any std nor expose any IO function, so you can build your own host (the VM) that expose functions that can be imported from the Wasm binary, that means that the Wasm binary can have access to the external world only through these functions.

Also I would say an advantage is that the binary format is not proprietary and there's a spec, so anyone could implement their own Wasm VM.

But right now is not in a good place yet, is too early and there are a lot of new functionality that is being standardized by a group (similar to W3C) and the process is very slow.