--- label: 'Managing height, width, and resolution breakpoints' related: - core.appearance ---
{% trans %}Breakpoints are the point at which your site's content will respond to provide the user with the best possible layout to consume the information. A breakpoint separates the height or width of viewports (screens, printers, and other media output types) into steps. For instance, a width breakpoint of 40em creates two steps: one for widths up to 40em and one for widths above 40em. Breakpoints can be used to define when layouts should shift from one form to another, when images should be resized, and other changes that need to respond to changes in viewport height or width.{% endtrans %}
{% trans %}Media queries are a formal way to encode breakpoints. For instance, a width breakpoint at 40em would be written as the media query "(min-width: 40em)". Breakpoints are really just media queries with some additional meta-data, such as a name and multiplier information.{% endtrans %}
{% trans %}Resolution multipliers are a measure of the viewport's device resolution, defined to be the ratio between the physical pixel size of the active device and the device-independent pixel size. The Breakpoint module defines multipliers of 1, 1.5, and 2; when defining breakpoints, modules and themes can define which multipliers apply to each breakpoint.{% endtrans %}
{% trans %}Breakpoints can be organized into groups. Modules and themes should use groups to separate out breakpoints that are meant to be used for different purposes, such as breakpoints for layouts or breakpoints for image sizing.{% endtrans %}
{% trans %}The Breakpoint module allows you to define breakpoints and breakpoint groups in YAML files. Modules and themes can use the API provided by the Breakpoint module to define breakpoints and breakpoint groups, and to assign resolution multipliers to breakpoints.{% endtrans %}