Users that download your app from unpaid sources
Unlike paid traffic, where users discover apps from advertisements, organic installs are often driven by word-of-mouth or keyword search on an app store.
Organic users are considered higher quality users in terms of ROI and LTV. However, it is much more difficult to obtain organic users over paid users due to the competitive nature of the app stores.
There are several ways to increase your chances of organic installs through app store optimization.