How siloing works
A silo is a themed group of pages that behave as one unit. A hub page introduces the subject, child pages cover its parts, and the links between them run mostly inside the group: hub to child, child back to hub, child across to a sibling where the reader would genuinely want it. Section folders in the address and a matching menu usually mirror the grouping, but the linking is what does the work.
The idea is that a search engine reading a tightly linked cluster can see what the section is about and which page is the main entry point for it. Instead of a dozen pages each mentioning the topic loosely, one clear hub gathers the theme and the internal links say which page answers which question.
Why siloing matters
Its real value is that it forces the awkward editorial decision most sites avoid: what is this section actually for, and which single page owns each search intent? Working that out usually turns up two or three pages competing for the same query, and merging them helps more than any link change would.
For a reader, a well-built silo makes a subject browsable. Someone who lands on a narrow page from search can see the wider section above it and the neighbouring answers beside it, which is often what turns a visit into an enquiry. It also gives new pages an obvious home, so a section stays coherent as it grows rather than sprawling.
Where siloing goes wrong
The strict version is the problem. Some older advice says a silo must be sealed — no links from one section to another, because linking out supposedly leaks value. In my experience that produces sites where a reader cannot get from a service page to the case study that proves it, and it treats internal linking as a tank of fluid rather than a set of signals about relevance. Where a cross-link is genuinely useful to the reader, put it in.
The other failure is silos built around wishful keyword groupings instead of real demand, so a section is invented for a theme nobody searches. And thin silos: a hub with two shallow children looks like structure but adds nothing a single strong page would not have done better.
How to act on it
Map demand before you draw boxes. Take your keyword research, sort it by search intent, and see which intents cluster naturally — the sections will usually be obvious, and they rarely match your internal department names. Assign one page per intent and write down which page owns it.
Then build the linking. Every child links up to its hub with a descriptive anchor; the hub links down to every child; siblings link across only where the reader benefits. Keep cross-section links for the places they help, such as pointing from a topic to the relevant service. If you are structuring an editorial section this way, the same discipline sits behind good content SEO, and it pairs closely with a sensible site architecture rather than replacing it.