There are two main ways of using search engines (Google, Yahoo, Bing and others) to drive traffic to your website:

Organic search results.

Paid search results.

Organic search is free. It's organic because where your site lists changes depending on a range of factors, many of which are out of your control.

Paid search results means you pay a fee for the search engines to display a link to your website. These are also referred to as pay-per-click or PPC advertising because you (the advertiser) only pays when someone clicks on your ad. Because many businesses rely on organic search, there is less competition for a paid listing, so it is more likely that you will be listed higher.

Which is better?

Organic search is free, and provides better value in the long term if your site is well optimised and performs well in terms of search list ranking. But it does take time (i.e. months) and quite a bit of effort if you are in a competitive market.

Paid advertising is more immediate and easier to track so you can get a better feel for the success and return of a campaign. In an ideal world, you would choose to do both, but it depends on your budget.