In-Theme Links

• In-theme links are links from other pages that relate to your website's industry or topic. In-theme links for a camping website include backlinks from from camping forums, blog posts about camping and other camping sites. Note that a site as a whole doesn't have to relate to yours for an in-theme link, but the page linking to your site should be related.
  
  

Off-Theme Links

• Off-theme links do not relate to a link's topic or industry. Examples of off-theme links for a camping site could include a horse website, a personal blog and even a canoeing site. Determining whether or not a link is off-theme is subject to individual discretion, but strictly speaking an in-theme link must be directly related to the target site.
  
  

Backlinks and SEO

• Obtaining backlinks is a critical component of search engine optimization (SEO), the process of optimizing your website so that it ranks higher for search terms on sites such as Google, Yahoo and Bing. Search engines analyze backlinks to determine the subject matter of your site. For this reason it is important for your site to have many quality in-theme links, otherwise it will be much harder for it to rank well on search engines. Off-theme links carry a smaller weight for SEO, so you should focus any link building campaign on in-theme links whenever possible.
  
  

Backlinks and Traffic

• Both in-theme links and off-theme links attract visitors to your website. It is still worthwhile to have a link on an unrelated site simply for the click-though traffic it creates. That being said, traffic from in-theme links is still better. Visitors coming into your site from related sites are more likely to have an interest in your content. Campers from other camping sites will likely find a new camping site useful. The same can't be said for visitors reaching a camping site through an automotive site. Of course, this doesn't mean you should ever turn down an off-theme link. Any link from a quality site is a link worth having.