Definition: Guest Blogging is a content marketing and SEO technique where someone writes and publishes a blog post on a third party website or blog to promote their personal/corporate brand. Guest blogging sites expose brands to a relevant audience and can be an effective method to generate awareness — but it must be done carefully to avoid Google penalty.
Guest blogging can be a mutually beneficial arrangement: publishers want quality content to feed their audience and keep them coming back, while authors need a platform to promote their brand. Truly informative blog posts accomplish both objectives by demonstrating the author's expertise on a topic and giving the publisher essentially free content. Online retailers can be on either side of this equation — they want to build up content and get their brand in front of a new audience.
Guest blogs are generally not excessively promotional - instead, they're best used as a means to educate the audience and provide insight on a topic, making guest blogging an inbound marketing strategy.
Aside from brand and inbound marketing benefits, guest blogging is a method to obtain inbound links. By writing a post on another website's blog, the author could benefit from passing PageRank (or "link juice") to their own domain. Like all SEO techniques, it has been abused. Former head of Google Webspam Matt Cutts specifically targeted this technique, deeming it a cause for Google penalty and no longer effective.
This does not mean that guest blogging can be done without penalty and doesn't offer considerable benefits. Rather, it must be done with care and user intent in mind.
Find the right audience: Thought leaders, partners, and interested parties are great places to start. Think about who their audience is and how much overlap they have with your own customer base. For example, a fashion retailer may publish a guest post on a popular men's clothing blog.
Write something unique: The purpose of writing a quality blog post is to entice readers to find out more about who you are and what you offer. The best way to do that is not write something they've seen countless times across the web, but to save the juiciest topics for guest blogs. Subjects and titles that not only encourages viewers to click through, but also take an angle or offer an approach that hasn't been done before.
Don't link back more than once: An author bio or a link to content on your website are simple ways to link back to your website — but you can err on the side of caution by avoiding both. To be truly cautious, insist that links back to your website have the nofollow attribute applied. That means you reap the promotional benefits and sacrifice SEO for the sake of ensuring a penalty-free interaction.
The same reasons that other websites may accept your guest posts apply to every publisher. Partners, fans, and and thought leaders may want to bolster their reputation by appearing on your blog. The key consideration is deciding whether or not a potential guest can genuinely contribute something to the company's audience. Evaluate whether you have a content gap that an guest blogger could help fill - for example, an online store selling unique toys for children might accept a guest blog from a child psychologist explaining which types of toys work best for different personalities.