This document discusses data visualization libraries for the web. It introduces Altair, which allows creating Vega and Vega-Lite specifications in Python. Altair provides a declarative API to map data to visual properties and marks. Specifications can be rendered in Jupyter notebooks or embedded in web applications using Vega-Embed without dependencies on the backend technology. The document demonstrates integrating Altair charts generated from a backend API in a Vue.js application.