If you think of your website as a map, navigation labels name the streets, features, shopping districts, and even major buildings like libraries and community centers. Does that description sound too expansive for something so humble? Maybe you need to rethink your definition of navigation labels.
As Shari Thurow explains on Search Engine Land, most people think of the text placed on a navigation button as a navigation label. Keep in mind, however, that most site visitors and searchers use multiple cues to orient themselves, and to make sure they ended up where they intended to go. Thurow's list of navigation labels includes the common definition I described, plus titles; headings and subheadings; breadcrumbs; embedded text links (in context); and URLs.
What is the point of expanding this definition? It gets you thinking about all of these different page elements at the same time. If you can see what they have in common, and think of them as belonging to the same group, you'll give them a more consistent structure.
Consistency helps anyone trying to navigate anywhere; it creates and fulfills expectations, and enables visitors to predict what they'll find when they click through or read something just by looking at the navigation label. Or as Thurow puts it, “When navigation labels contain keywords and are used consistently throughout a website, they effectively communicate aboutness of both page and site content, as well as provide a clear information scent to content that is not available on the web page.”
So now you understand how treating these very important page elements as aids to navigation can make your human visitors happy. They can also make the search engines happy. When spiders crawl your web pages, if they see a consistent structure to your navigation labels, with a predictable usage of keywords, you've made it easier for them to figure out your site's relevant topics. To put it bluntly, using navigation labels correctly can help your site's SEO.
The key point, however, is to use navigation labels correctly. This goes beyond simply putting keywords in your URLs. Fortunately, there are a number of prevailing conventions on the Internet for structuring your navigation labels.
Search Optimization 
