Motoko compiles to WebAssembly (Wasm) due to its versatility to operate across the internet. The Internet Computer leverages Wasm Canister smart contracts to store data and execute code directly to the internet. Wasm is a binary instruction format for a stack-based virtual machine. It is designed as a portable compilation target for programming languages, enabling deployment on the web for client and server applications.
For these reasons as well as its compatibility across browsers, Motoko compiles down to Wasm. Additionally, any language that can compile down to Wasm can then be deployed on the Internet Computer.