I have just started running adwords campaign. My question is the keywords I select in adwords, do they have to be in the main page of the my website. In order words if a site about is cars and I run a campaign for keyword Acura, do I need the word Acura on the main page?
You can actually make the landing page any page on your website. So you can setup landing pages for each of your specific keywords that are specific to their own content.
While you don't have to have the keyword you are targeting anywhere in your landing page it will help with your quality score which effects how much you pay for clicks and where you are placed in relation to the other adwords ads you are competing with.
I will agree with shauner that it will help keep cost down, so I would say it is essential in my view to have several versions of the same landing page and tightly focused keywords going to landing pages that have that keyword in the text of the landing page.
The biggest thing I think is thinking about how the person who clicks the ad is going to react. If they click on your ad thinking they are being taken to a page called "acura" and end up on a page where there is nothing in the text to suggest its the case - they are more then likely to use their back button. I know when I browse through ppc ads I have a trigger-happy finger on the back button. Unless the promise of the ad is met by the content of the landing page I think you are doing yourself a dis-service. Dylan