WebAssembly

WebAssembly is a portable binary instruction format for a stack-based virtual machine. It is designed as a compilation target for high-level languages such as C, C++, and Rust, enabling web and non-web environments to execute code with near-native performance. WebAssembly modules are designed to be executed in a secure sandbox by the host, with performance optimizations performed by the runtime engines in browsers or other environments.

A WebAssembly module contains code and a linear memory, and it exposes functionality through imports and exports. Memory is a contiguous, byte-addressable region, and function references can be stored in a table. WebAssembly is intended to be independent of the underlying hardware and operating system, allowing the same module to run across different platforms. Engines may compile modules ahead of time or Just-In-Time to machine code for execution.

In the web ecosystem, WebAssembly runs alongside JavaScript. It can be loaded, compiled, and instantiated from binary or text formats, using APIs such as WebAssembly.instantiate and WebAssembly.instantiateStreaming. It interoperates with JavaScript, enabling calls in both directions and sharing of memory, while still benefiting from a secure sandboxing model.

The technology emphasizes safety, portability, and performance. Its sandboxing and memory model provide security guarantees, and its optimizations give near-native execution speed for compute-heavy tasks. The WebAssembly ecosystem includes standards, toolchains, and integrations for both browser and server environments, with ongoing work to expand features such as multi-threading, SIMD, and external system interfaces via WASI (WebAssembly System Interface).