It's an important reminder for us all now and again to talk about how Google works in regards to ranking your entire website. As you can see from the title of this post Google does not rank "entire websites", but they do rank all the pages of a website individually.
Why is this important for me to know?
When you are starting to create your website (in the first few steps of design) you should keep in mind that every page you create has the potential to get ranked. Because of that, if done properly, you have more pages that have a chance of getting rankings. Let me explain:
Lets say you create a great super-informative site with 300 pages loaded full of unique content teaching people how to protect themselves online. Well, if you make the mistake of using the same title tag, meta-description and meta-keywords on each and every page of the site, Google is (more then likely) going to be seeing all pages other than the homepage as a "supplemental result". That means its' hard for Google to give weight to a certain keyword or phrase on all the other 299 pages since you are using the same information in these areas. In other words, if all pages are using the same meta info, Google can't help you rank good for a specific keyword or phrase since all pages are going after the same words. However, if you are able to use different words on every single page it makes it easier for them to rank you for more keywords and phrases.
This can lead to more traffic, and the ability to be ranked for more than just one or two words. Also, you can get more than just your homepage ranked for certain keywords and phrases.
There are certain pages that really do not need to be optimized such as the "about us" or "contact us" pages. Those pages are mostly created for people that have found your site to know who they are dealing with and how to get a hold of you in case they need to!
In conclusion, make sure you are making your content unique on all pages as well as the title tag, and all meta tags. Obviously there are way more steps to onsite optimization, but even following these simple rules can help you get more pages ranked, have the ability to go after more keywords, and in turn get more traffic!