How to handle tertiary and quaternary navigation

1. What is tertiary navigation?
2. How many levels of navigation should a website have?
3. What is a primary navigation menu?

What is tertiary navigation?

Contextual navigation (also known as tertiary).

Contextual navigation supports content by providing specific options. Those can be local links for product details pages on a search results page.

How many levels of navigation should a website have?

Most often, there are three or four levels of hierarchy for most websites. This keeps things accessible, while making sure the site navigation isn't too broad.

What is a primary navigation menu?

Primary navigation is the principal navigation interface on a website. It links to the most important website pages and appears prominently at the top of the homepage and other pages. Primary navigation helps users to quickly find what they're most likely to want, with minimal searching and clicks.