Press Release Submission is closely similar to article submission. The only difference is that Press releases are more commercial in content compared to articles which should be informational.
Press release submission is a good way of getting tons of backlinks in a short period of time since a press release submission site usually syndicates content to over 500 other sites, which gives you an opportunity to gain 500 backlinks in an instant.
When writing a press release, it should consist of a company event, a product release, a website redesign, or something that is newsworthy.
