under the hood

adj. [hot-rodder talk] 1. Used to introduce the underlying implementation of
a product (hardware, software, or idea). Implies that the implementation is
not intuitively obvious from the appearance, but the speaker is about to
enable the listener to grok it. Let's now look under the hood to see how.
... 2. Can also imply that the implementation is much simpler than the
appearance would indicate: Under the hood, we are just fork/execing the
shell. 3.

