WASM is supported in all modern browsers.
Why we should care about WebAssembly?
It provides a way to run code written in multiple languages on the web at near native speed.
Watch this video from Mozilla.
Is it a web standard?
WebAssembly is an emerging standard, with ongoing work on the specification. The browser vendors have reached consensus on the design of the initial wasm API and binary format, and it is being developed as a web standard with an active group via W3C WebAssembly Working Group with members from Mozilla, Microsoft, Google, and Apple.
The key words are low-level. It defines primitives including a range of types and operations on those types, literal forms for them, control-flow, calls, a heap, etc…
These are very simple primitives, No complicated object system, No built-in automatic garbage collector following you around and stopping you periodically while it cleans up your scraps.
An important fact to know is, WebAssembly is backward compatible. In fact, there is no versioning.