Why is Search Engine Optimisation important? Imagine you have a company selling cars online. And then say for example the search term "Buy Cars Online" had 10,000 searches a month on a popular search engine, such as Google. Wouldn't you want your website to be found when that term was searched?
Unlike traditional mass marketing, where you are sending a message to everyone and hoping someone is relevant and interested, with Search Engine Optimisation (SEO) you are bringing traffic to your site that is already interested (or why would they have typed the search query in). So your website is no longer convincing potential customers to buy, you are just convincing them to buy from you. And the higher your placement in the search engines, the higher the authority of your website is perceived as having.
There are a lot of scams out there with companies claiming to be able to guarantee you a first position on search engines. This is impossible to guarantee. But with appropriate strategies and the right person running your Search Engine Optimisation campaign, and a realistic time-scale, there is no reason why your company cannot get to the top positions on search engines, and teh benefits that come from that position.