Clarify some wasm terms in the introduction (#8115)

* Clarify some wasm terms in the introduction

* Update docs/introduction.md

* Update docs/introduction.md

---------

Co-authored-by: Nick Fitzgerald <fitzgen@gmail.com>

docs/introduction.md

@@ -1,10 +1,36 @@
 # Introduction
 
-[Wasmtime][github] is a standalone optimizing runtime for [WebAssembly],
+[Wasmtime][github] is a standalone runtime for WebAssembly, WASI, and the
-[the Component Model], and [WASI] by the [Bytecode Alliance][BA]. It runs
+Component Model by the [Bytecode Alliance][BA].
-WebAssembly code [outside of the Web], and can be used both as a command-line
+
-utility or as a library embedded in a larger application. Wasmtime strives to be
+[WebAssembly] (abbreviated Wasm) is a binary instruction format that is designed
-a highly configurable and embeddable runtime to run on any scale of application.
+to be a portable compilation target for programming languages. Wasm binaries
+typically have a `.wasm` file extension. In this documentation, we'll also use
+the textual representation of the binary files, which have a `.wat` file
+extension.
+
+[WASI] (the WebAssembly System Interface) defines interfaces that provide a
+secure and portable way to access several operating-system-like features such as
+filesystems, networking, clocks, and random numbers.
+
+[The Component Model] is a Wasm architecture that provides a binary format for
+portable, cross-language composition. More specifically, it supports the use of
+interfaces via which components can communicate with each other. WASI
+is defined in terms of component model interfaces.
+
+Wasmtime runs WebAssembly code [outside of the Web], and can be used both as a
+command-line utility or as a library embedded in a larger application. It
+strives to be
+
+- **Fast**: Wasmtime is built on the optimizing [Cranelift] code generator.
+- **Secure**: Wasmtime's development is strongly focused on correctness and
+  security.
+- **Configurable**: Wasmtime uses sensible defaults, but can also be configured
+  to provide more fine-grained control over things like CPU and memory
+  consumption.
+- **Standards Compliant**: Wasmtime passes the official WebAssembly test suite
+  and the Wasmtime developers are intimately engaged with the WebAssembly
+  standards process.
 
 This documentation is intended to serve a number of purposes and within you'll
 find:
@@ -21,8 +47,9 @@ contributions are welcome!
 
 [github]: https://github.com/bytecodealliance/wasmtime
 [BA]: https://bytecodealliance.org/
+[Cranelift]: https://github.com/bytecodealliance/wasmtime/blob/main/cranelift/README.md
 [WebAssembly]: https://webassembly.org/
 [WASI]: https://wasi.dev
 [outside of the Web]: https://webassembly.org/docs/non-web/
 [issue]: https://github.com/bytecodealliance/wasmtime/issues/new
-[the Component Model]: https://github.com/WebAssembly/component-model
+[The Component Model]: https://github.com/WebAssembly/component-model