CSS3 selector can be used to select an element based on the tag, class or id.

Creates a selection with the first element that matches the selector.

d3.select("div") will match the first div element that it finds.

Like d3.select but will get all nodes that match the selection, even if they are nested.

Selections can be chained: d3.select("#main").selectAll("p").

With any selection you can call .nodes() to get all the actual nodes. Example: d3.select(".centered").nodes()