Hey there, Ricky! Tawny from Moz's Help Team here.
We use several different sources for our search volume data, including Keyword Planner and anonymized clickstream data. From there, we built a model that predicts the search volume range a keyword is likely to have with ~95% accuracy. For the nitty gritty details explaining how the model works, check out this article: https://moz.com/blog/sweating-details-google-keyword-tool-volume
You can read more about the Keyword Explorer Metrics in our Guide.
I've also got a few resources about keyword research and keyword strategy that might be helpful:
- The Keyword Research guide is a really good place to start if you need a refresher course!
- There's a great post in the Moz Blog about creative free keyword research
- If you're looking for insight into competitor keywords, try heading over to Open Site Explorer, pop in your competitor's URL, and take a look at the anchor text associated with their links. This can be a huge indicator of targeted keywords, which you might now decide to compete for!
- If you're curious how well you (or a competitor) is ranking for a certain keyword, or how well a certain page on your site ranks, hop on over to the Rank Tracker
- Use the Keyword Explorer tool to check how hard or easy it will be to rank for a certain keyword. Words with a higher difficulty score are harder to achieve rankings for, so some users will target lower difficulty words first and later tackle the hard ones. Something different works for everyone, though!
- When you've got your keywords and are ready to optimize your pages for them, check out the On-Page Grader. This will check a particular URL for optimization with a particular keyword or keyword phrase, and offer a grade based on how well it fares, as well as suggestions for improvement.
I hope that helps! If you've still got questions about the volumes you're seeing, feel free to shoot us a note at help@moz.com and we'll do our best to answer all your questions in more depth.