If you still don't get what 'topic clusters' are, it's okay. At first, Neither did I (completely). But from what I do understand, they're an incredibly cool and nifty tool to help you get ahead of the game, and/or to help your content help itself.
First of all, understand that a topic cluster is a tool and also a strategy primarily used in and developed for marketing on the internet. It's a system and concept that involves multiple steps and multiple facets and is usually applied to websites. To simplify what topic clusters are, let's break the term down. A cluster is “a group of similar things'' or simply just the word “bunch”. So; a bunch of topics. Specifically, a bunch of topics to not just answer a user's question, but to hopefully further expand on what they had in mind with several relevant subtopics and topics of interest.
Moving on, do you remember how you used to use internet search engines, and they hardly seemed to understand what exactly you were trying to look for? Remember the off-point search results and the extra time you spent wading through the results pages?
Fundamentally, search engines would use your keywords individually to find the closest and most accurate thing they think you're looking for. Rather than understanding you through individual keywords, Hubspot (the creators of this wonderful system!) made it possible for search engines to understand you through the sentences (or group of words you strung together before hitting 'Enter') you type to bring you more specific and relevant results. Keep in mind that people use search engines as a means to have their many questions answered and being in the business of answering those questions as best as possible is an actual job, as well as being able to do that will help position the link to your website higher up in search results.
Previously under the "older way of doing things", any given search engine’s SEO (Search Engine Optimization) technology would scour the internet through individual keywords, ignoring context and whatever words were next to it, which inevitably brought irrelevant and random content up in search results making this harder for the technology to be effective. Creators and entrepreneurs would be forced to put out more content in order to increase their odds of showing up better and ranked higher in internet search engine results. Thankfully there is a more updated way of doing this considering the context, sentences and terms, and specific long-tail keywords.
Known as content clusters or a content hub, this method is a popular marketing tool used to enhance and boost your website’s traffic through SEO. However, the topic cluster SEO focuses on topic optimization rather than keyword optimization, which aims to and would result in boosting your website's ranking and visibility in search engine results and improve on your website’s overall architecture.
You start with creating the landing page as the main lobby, which attempts to answer user questions in a more general sense. Then, linking more pages that explore more in-depth topics or subjects in the same vein on the landing page (obviously relating to your business or matter of expertise) in order to better satisfy the user's need or question; that is what a topic cluster is.
A topic cluster can consist of many pages and sub-pages as well. These are categorized into two parts; the pillar pages (main content page) and cluster pages (sub-pages to the main content page and a.k.a. the cluster topic). Think of pillar pages as a hotel lobby where you receive and welcome guests, and cluster pages as hotel rooms for your guests to enter. Pillar pages are the core that serves as an introduction to the main topic of your business or subject matter while allowing access to the sub-topics that are (hyper-linked) linked on the pillar pages, allowing ease of navigation and increasing time spent on or with your content. There's more relevance to explore, and one usually feels that they're already there so why not partake in it. Furthermore, these pillar pages allow for expanded sub-topic content and categories within the main page to exhibit and expound on the whole subject, cater detailed information, and assemble a thorough keyboard frequency throughout your website for admissible search conclusions.
Other than better engagement on your content, users will have more accurate results on search engines, creating improved user-friendly accessibility of your website. With a well-kept lobby and tidy rooms all organized and neatly arranged through the implementation of topic clusters, you now have a well-oiled machine that's ready to go, and receive. I suppose at this point, you could think of topic clustering as the hotel management and housekeeping in a way. Your hotel is now ready for business, and better business! Go forth and go well.