Google refers to the technology as a way of evaluating the usefulness, importance, and quality of a website. The PR of a webpage can mean different things for different people.
For a webmaster, a high PR is a sign of accomplishment. It shows that your website is moving in the right direction and has the potential to become successful. PageRank also directly effects your Google search engine listings. Acquiring a higher PR than your competition could mean more traffic for you, and less traffic for your competitors.
Visitors to your website probably won't care about the page's rank (most surfers have no idea what PageRank is). However, visitors who understand PageRank may use your PR as a sign of how credible your content is. Would you rather use the information from a website with 0 PR or a website with 5 PR and hundreds of other websites linking to it?
PageRank is basically determined by backlinks. A backlink is when another page links to your page. For every page that links to you, that page is "voting" for you. The more votes you get, the better your PageRank will be.
However, it gets more complicated than that because some votes weigh more heavily than others. The weight of the vote is determined by the PageRank of the page linking to you. This means that a couple links from pages with high PR may be more beneficial than hundreds of links from pages with low PR. But it gets even more complicated - each page can only transfer so much PageRank. This means that a PR 7 page could actually give out as much weight per vote as a PR 3 page if it had too many outgoing links.
Google also uses factors totally irrelevant to backlinks to determine PageRank. An example of this is how long your domain has been registered for. It would be good to look into these factors if you want to maximize your potential PageRank, but quality backlinks are still more effective.
There are many different methods to obtain quality backlinks to your website. You will find that some methods work better than others depending on the subject and popularity of your site.
Directories
Submitting your website to directories is one of the best ways to increase your PageRank and even get some traffic at the same time. But submitting your site to just a few directories won't be good enough. You need to sit down and spend the necessary time to submit your site to a large amount of directories. This may seem like a painstakingly long process, but you'll be glad you did it when you notice results. I have taken the time to make a large list of free directories with high PageRank which you can get to by clicking here. Although directories with low PR may seem like a waste of time, you should submit your site to them too because it still helps and they could eventually become a high PR site which charges money to submit to.
Link Exchanges
A very common practice to improve your PageRank is a link exchange. This is simply where two people link to the other person's website. It's best that you only link exchange with someone who has at least as much PR as you and the subject of the two websites are similar. If you receive a link from a website with a subject which has nothing to do with yours, you'll find that very little if any PR will actually be transferred to you.
Forum Signatures
If you are an active user on a forum or message board, it would be wise to put a link to your website in your signature. This could help improve your PageRank if the forum has a high PR, it could help improve your traffic from the forum members seeing your signature, and your site could get spidered more often because it's linking to a forum (forums generally have a lot of new content every day and search engines love new content).
Buy Advertising
Although it isn't the best of choices, many webmasters will buy text link ads on websites with high PR. Although this can be effective, it can be very expensive and only a temporary thing. If you purchase text links for just a couple months, after the months are over you won't have the backlinks which were giving you the "votes" you needed to keep your PageRank. So you have now spent a large amount of money on text links, but in the end you're right back where you started.
Articles
This is a method which not many people know about. Basically, you write articles about the subjects you know a lot about. You then let other people use these articles as long as they provide a link back to your site. If you wrote a quality article, you'll find many websites will want to use it, thus giving you plenty of backlinks. This method can work well with anything which you develope and give away for free such as scripts, web design, etc.
Stay On Google's Good Side
The most important thing to remember when trying to increase your PageRank is to not cheat and to always follow the rules. The people which run Google aren't fools and they have many ways of catching cheaters. Don't even think about using any of the "link farms" or trying to hide keywords on your pages. If caught, you may not get unbanned for many months.
Make A Quality Website
If you have a quality website which your visitors enjoy going to, then you will receive backlinks without having to do anything. Websites will link to you with the intention of informing people of a helpful resource, or showing off a cool new website they found, or any other reason other than trying to increase your PageRank. If you build it, backlinks will come...