Using Google keyword planner to estimate your market size (and more)

Just as an for some extra context:

Google's keyword planner tool can be used to quickly gather the following useful data: -Relevant keywords for your product or niche -Market size (using Google search volume as a rough estimate) -Market share (how many clicks you'll actually get using adwords)

All useful stuff for validating a product or business idea BEFORE launching. This is also known as a "bottom-up" market size analysis.