¡¡¡¡Yes. Every page of the website need to be optimized. Every page of a website can be a potential entry point for visitors. You can't predict which page or pages will be ranked the best for specific keywords. So each page must be individually optimized to for optimal ranking. Collectively, all pages of your website reinforce the common "theme" of the site, which also can help boost ranking. Don't assume that your home page is the most important page on your site.
¡¡¡¡Search engine optimization (SEO) is the process of improving the visibility of a web site or a web page in search engines via the "natural" or un-paid ("organic" or "algorithmic") search results. Other forms of search engine marketing (SEM) target paid listings. In general, the earlier (or higher on the page), and more frequently a site appears in the search results list, the more visitors it will receive from the search engine. SEO may target different kinds of search, including image search, local search, video search and industry-specific vertical search engines. This gives a web site web presence.