You can automatically search through many websites without actually going to those sites, as long as they're in your list of search engines. This trick is beneficial if you wanted, for example, to go directly to a WikiPedia article without going to WikiPedia's front page first.
Go to 'Settings->Search engine->Manage search engines' to see a list of all the search engines already available. If the Website you want is not in the list, you will need to add it before using this feature. To do so, go to the website you want to add and click on the Search button (you don't need to actually type anything in) then copy the path from the address bar so you can paste it later.
Go back to Manage search engines and click on 'Add' located to the right of Other search engines. Enter the Search engine and a Keyword then paste the link you copied earlier into URL. Add %s at the end of the link then click on the Add button.
Now, when you type the website into the Omnibox (example: wikipedia.org), you'll see a prompt telling you to press Tab to search within the site. Once you press tab, you'll see 'search (site name)' written in blue on the left side of the Omnibox. Type in your query and Chrome will only search within that site.