Press releases are often used by companies to generate publicity. They are usually in the form of one typed page, and directed towards those who work in the news media. For a press release to be "picked up" it must be considered newsworthy. If it sounds like a dressed up sales letter you can bet it won't be read and published. The media's job is to publish news, not fluff. There's a certain format that most journalists look for in the layout of a press release and effective releases will adhere to this strict standard.
There are many ways to distribute a press release. They can be mailed, faxed, and even emailed. One can hire an outside service to do this, or a little online research will yield hundreds of press release submission sites to submit to.
People who write press releases will find plenty of blogs that will be informative about the press release process and its benefits. If one writes press releases and includes keywords that are related to one's website and then posts the releases online, they can also help with search engine ranking.