Uncontrolled Components

One Source of Truth (the DOM)

Instead of handling data within the component, using either state or props, the data is handled by the DOM itself. It isn't really that complicated, basically instead of having some state handling an input field value, the DOM uses the "value" attribute, and this can be fetched from the DOM using refs.

This is a good approach when trying to combine React and non-React code, since you can use the DOM to be the one source of truth rather than state and something which well, doens't have any.