Just for a moment set aside all the spammy cheating ways you can make a website rank. Forget about black hat, forget about link farms, forget about hacking sites to seed links, posting stupid meaningless comments in forums and forget about buying a shed load of links. Just simply ignore all that stuff, just for a moment, just for me.
Go it? Good, then I'll begin...
When Google started indexing the web they realised they needed something that would automatically assign a quality score to every page. They needed a mechanism for automatically, using a computer program, ranking pages in order of importance. It wasn't possible for humans to do this, there were already too many pages, and anyway, one man's meat is another man's poison. No, they needed their indexing software to be capable of making a value judgement on the pages it was indexing.
Being a couple of egg heads (by the way did they ever finish their PhD's?) the concept of citations was something they were comfortable with. For the non egg heads I'm talking about the way academics reference each others work, that is to say the way Dr Smith writing a paper will make reference to a paper written by Dr Jones.
Ah.....they thought.....surely if web page A links to web page B then A is effectively citing or endorsing B. Effectively a link from page A to page B is like a vote of confidence. And bingo, the link based algo was born. The link based algo is effectively a merit based system allowing pages to be voted up the rankings.
So, and remember for the moment we're all ignoring all the trashy stuff, your job as a website owner is to create web pages that are likely to compel other people to link to them. If you do this your pages will be voted up the rankings as it's effectively a merit based algo that uses link popularity to measure page importance.
So why the history lesson? Well basically we have lots of conversations with companies about their website's non appearance in Google and it's pretty obvious they haven't got a scoobie about how Google ranks pages and to be honest a lot of them don't seem to understand the concept of a meritocracy either!
Going to the trouble and expense of building a website doesn't give you any sort of right to appear in Google's search results. Google's not like a telephone directory where simply having a number ensures a listing. If you want to move forward you have to get your head round this simple fact.
Of course from there you can use all of the scummy techniques mentioned previously, and why not, everyone else is, but it helps if you at least understand where Sergey and Larry are coming from.