A Five-Minute Intro D3.js 

BIND SOME DATA Select a set of elements and associate them with a data set 

Data can be as simple as an array of numbers... DATA? Or more complex JSON objects 

USE THE ENTER() SELECTION For each element in the data set, we append a new circle to the initially-empty selection 

MAKE THE DATA PRETTY Use .attr to set attributes arbitrarily, or based on values from the data object bound to each element 

MAKE THINGS FIT Scales map values from an input domain to an output range 

MAKE THINGS MOVE Use transition() to change attributes of an element over time