One of the most important aspects of having a website is search engine optimization. It's a crowded playing field out there, and depending on how wide or narrow your site's products or services are, you could be up against some serious competition. I have a website that is pretty good, but the competition for keywords is so intense, so I need to do website optimization nearly every day. Keeping a site at the top of the list among hundreds of thousands or millions of other pages is something to take seriously when you have a website.
If your search engine optimization has put you at the top in the major search engines, your website marketing budget can be much smaller than if you have to use pay per click ads. These ads are often abused by competitors, who will click on them just to run up your budget, so the importance of great search engine optimization cannot be stressed often enough. Instead of paying to drive traffic, you will be able to get your traffic for free, always a great alternative to paying for something.