Confused by terminology

I’m trying to learn d3.js and started the first challenge: Visualize Data with a Bar Chart. It says:
Objective: Build a app that is functionally similar to this:

Is “build an app” just the lingo in d3. It just means build the barchart, right?

“Build an app” means “create a web application”.
“Application” /“app” is an overloaded term, but for this purpose you can consider it to be anything beyond a simple, static web page.

Just an interactive bar chart on a web page is considered an app, then. Thanks. Javascript pocket reference: “Client-side javascript exists to turn static HTML documents into interactive web applications.”