React uses a declarative paradigm that makes it easier to reason about your application.
React minimizes interactions with the DOM by using a mock representation of the DOM.
React works with the libraries and frameworks that you already know.
React components implement a `render()` method that takes input data and returns what to display. This example constructs the component using an XML-like syntax called JSX. Input data is passed to the component as XML attributes, and `render()` accesses this data via `this.props`.
In addition to taking data from its creator (accessed via `this.props`), a component can maintain internal state data (accessed via `this.state`). When a component's state data changes, the rendered markup will be updated by re-invoking `render()`.
Using properties and state, we can put together a small Todo application. React provides an interface to the DOM via `refs`. Although event handlers appear to be rendered inline, they will be collected and implemented using event delegation.
React is flexible and provides hooks that allow you to interface with other libraries and frameworks. This example uses Showdown, an external Markdown library, to convert the textarea's value in real-time.