Using the Extension Builder

Browser extensions are computer programs that add functionality to a
browser. They are not originally part of WebKit and are not supported by it.
Such support is viewed as more appropriate for each individual web browser
to handle.
Initially, Apple didn’t include the capability to run extensions in Safari. In fact,
it wasn’t until version 5 that they first appeared.
Extensions are add-ons to the browser that can be developed by anyone.
They can be used to modify how the browser works or to add functionality to
the browser.
You can view your installed extensions, and install new ones, in the
Extensions tab of the Preferences window.

The Extensions Builder is below the Develop Menu. Although outside the
scope of this book, if you’re adventurous and want to try your hand at creating
an extension of your own, you can do so here.