In order to rank well in search engines for both broad keywords (e.g., peanut butter) and longer, more specific keyword phrases (e.g., organic crunchy peanut butter), your website must have enough clearly organized supporting content to appear relevant for those terms. Search engines look closely at your site structure to determine your site’s main topics and whether there is enough keyword-supporting content.
Think about how farmers organize their harvests of wheat, barley, oats, and so forth. Farmers care for the integrity of their product by storing each specific type of grain in a separate silo. If wheat, barley and oats were all mixed together, the product would have less value, marketable only as generic “grain.”
Siloing a website means grouping related pages together, either structurally or through linking, to establish the site’s keyword-based themes. Much like farmers use separate silos to store different types of grain, webmasters can silo a website to distinguish its various content themes and make it clear to search engines what the site is about.
Siloing your site improves the relevancy of your web pages for your desired search terms. Links are strategically used within theme-focused sections of the site — and PageRank (i.e., linking value) gets passed between closely related pages and landing pages, reinforcing the themes. Rather than allowing the website to be viewed as a disorganized mixture with no keyword focus, a silo strategy reveals what the site is really about and helps position your website as an expert source for a given topic.
Search engines tend to award the top keyword rankings to sites with clear website structure and subject matter relevancy matching a user query. That doesn’t mean pages filled with exact keyword phrases. Especially in the era of Google’s Panda algorithm, which rewards quality content, you want to build your website around themes based on keywords, not just the keyword phrases themselves. Siloing that themed content is essential to SEO. Without further ado, here’s the nitty-gritty of siloing.
What Is Physical Siloing?
There are two ways to silo a website — physical siloing through the directory structure and virtual siloing through the linking structure. Let’s discuss physical siloing first.
The URL address of a web page can give users and bots important clues about the page. For instance, the URL below reveals that the page focuses on some kind of cordless, hammer, power tool by Makita:
When you use the physical URL directory structure of a website like a filing cabinet to organize related pages, you are creating physical silos. Each theme of the site has a group of pages saved together under one folder dedicated to that specific category (e.g., “cordless”), and within that category are subfolders for the different subcategories (e.g., “hammers”). Each file has its place in a distinct category, with no two files ever getting filed into both categories, only one or the other. (SEO Tip: You don’t want the same page contents to be indexed under more than one URL.)
To have a physical silo structure, create a directory structure that aligns with the various themes covered within your website.
What Is Virtual Siloing?
Virtual siloing involves using the internal link structure of a site (i.e., how pages link to other pages) to:
- Connect groups of related pages together.
- Separate unrelated pages.
- Strengthen the primary landing pages of each silo.
While physical siloing requires theme-related pages to be located within the same directory of a site, a virtual silo is held together by hypertext links between theme-related pages. In fact, connecting related pages virtually through text links can be effective even in the absence of physical silos, because the search engine spiders crawl a site’s contents by following its links. Virtual siloing is powerful.
By linking between pages that are tightly related in topic and theme, you are consolidating that theme-relevance to a section of your site. A site hierarchy, with top-level landing pages and support pages for each SEO silo, emerges based on linking patterns alone. For example, rather than interlinking between all of the pages haphazardly, our example power tools website could use virtual siloing to show that it has three distinct, keyword-relevant content themes for cordless, electric, and gas-powered tools:
Support pages always link up to their silo landing page (indicated by the lines connecting all the blue pages together, for instance). Cross-links between silos should be avoided except to silo top landing pages (indicated by the larger rectangles in the example diagrams). Since random links between silos would weaken the theming, no subpage within a silo should link to a subpage in another silo. The diagram below shows appropriate and inappropriate internal linking for a siloed website:
Careful linking within your site shows the relationships between pages, reveals your website’s topic structure, and strengthens the keyword relevance of your main landing pages, which are the ones you want to show up in search results. Virtual siloing leads to the accumulation of PageRank on the top-level landing page of each silo, which becomes the most relevant page on your site for keywords related to that theme. This is how siloing leads to better search engine rankings.
We recommend using the virtual silo approach reinforced by the physical silo approach when possible, for maximum effectiveness.