Example of the 'Accordion Menu' pattern

User needs to navigate among a website's main sections while still being able to quickly browse to the subsection of another.

From canon.com.

From canon.com.

Other example images for the 'Accordion Menu' pattern

From canon.com. The Accordion menu used at apple comes in two versions: One that is instantly updated through the use of javascript, and a more static one, that is updated via a new page load.
From canon.com. The Accordion menu used at apple comes in two versions: One that is instantly updated through the use of javascript, and a more static one, that is updated via a new page load.