Make loading content in your app as delightful and painless as possible by minimizing the amount of visual change a user sees before they can view and interact with content. Each operation should only be represented by one activity indicator—for example, one refresh operation should not display both a refresh bar and an activity circle.

[Linear Progress Bars](https://www.google.com/design/spec/components/progress-activity.html#progress-activity-types-of-indicators) are created with the `<md-progress-linear>` directives.
