What is the `picture` Element?

The picture element is a markup pattern that allows developers to declare multiple sources for an image. By using media queries, it gives developers control as to when and if those images are presented to the user.

The srcset attribute is an extension to the existing img tag that provides some of the functionality of the picture element. It uses a more concise syntax, part of which may be used by the picture element.

What are the use cases for each?

The Use Cases and Requirements document outlines the goals, objectives, and potential issues for end users that must be solved by the picture and srcset extension specifications.