For some, a URL is just a unique finger print that holds the unique location of a web page on the internet. To an SEO expert, it holds much more information than a web page’s location. It provides informative signals that help search engines understand the content of a page, it’s purpose, and it’s target market. 
Like all signals, some can be weak, some can be strong, and some signals can even be missing. Below are the 10 most important signals that major search engines detect from URLs when determining the page’s content, who the target market is, and how high to rank the page in the search results.
how to optimize url for seo

Source: http://mysiteauditor.com/blog/top-10-most-important-seo-tips-for-url-optimization/