Siloing a website means grouping related pages together, either structurally or through linking, to establish the site’s keyword-based themes. Hopefully this will help simplify the answer: ‘Silo’ in terms of SEO is referring to the internal linking structure of your website. For example, let’s say you are a law firm that specializes in criminal defense and personal injury law. You could proceed to build a “silo” for each of those practice areas – a “criminal defense silo” and a “personal injury silo”. This would be achieved by linking all criminal defense related pages up to the top level criminal defense page, and linking all of the personal injury related pages up to the top level personal injury page.

In essence creating virtual silos within your website. The SEO benefit comes from the tightly knit pages of content around particular topics, which builds “topical authority” and transcribes into authority (rankings in Google) for keyword phrases related to your silors.