The theory goes that you have to do it right, however, and that's an involved process requiring super-expert knowledge. If you manage to do this, or have it done for you, you'll rocket to the top of the search engines and stay there, reaping rewards for many months if not years to come.
Pretty much this entire scenario is tosh. It's not set and forget for a start. It's much more of an ongoing process. And that's primarily a human (as opposed to technical) one. And while it's definitely worth knowing what you're hoping to rank for and structuring your site accordingly to make this as clear as possible to Google, this will usually only get you a little way.
Yet this unrealistic belief persists for some reason, and many web hosting companies exploit it. For example, you often see ads for web hosting packages that feature the claim: "Website comes optimized for search engines!"
But what does that mean, exactly? Optimized for which keywords? And to what extent?
It's clearly meant to make you think that you won't have to do anything yourself, that you're going to get Google traffic immediately or pretty soon thereafter. People believe this claim and that's why they're happy to hand over their money, sometimes a helluva lot of it.
Slowly it dawns on them that their expectations are not being met. But by then it's too late, they've bought the product. They realize that rather than being at the end of the process, they're actually at the beginning.
If you're one of these people and you want to achieve the optimization you thought you were already getting, but didn't, you'll have to do a whole bunch of things yourself.
Basically, you have to choose what keywords you're trying to get found for and build pages around them. Then you've got to build some links, as well as drawing relevant, voluntary one way links to your site (still a hugely powerful factor). You want to get some social sharing of your pages as well. When these factors are operating cumulatively -- among many others such as load time, age of domain, bounce rate -- and Google is getting some "good vibes" from your website, the hits will start to come. Only at that stage can it truly be said that your website is "optimized for search engines".