If you've never been on Product Hunt before, it's like a daily Reddit feed for new products. Products get submitted to the community and they're voted on. Each day products are stacked in descending order based on how many votes they've had. Ranking at the top of the daily list can result in thousands of conversion-focused traffic to your site, just as the creator of Nomad List found out.
Beyond organic and direct traffic, you must understand the difference between all of your traffic sources and how traffic is classified. Most web analytics platforms, like Google Analytics, utilize an algorithm and flow chart based on the referring website or parameters set within the URL that determine the source of traffic. Here is a breakdown of all sources: