Learn Android and UI-related terms.

In Android, an activity includes an app's UI and the actions it makes available to users. An app is a collection of activities that are created and reused from other apps. Read more on how activities allow for flexibility in the user journey.
Call to action, the primary goal you want your user to achieve. For example, Subscribe could be a CTA for letting a user to sign into a service.
Canonical layout
Commonly used design compositions that help layouts adapt for common use cases and screen sizes.
The colorfulness of a color, ranging from neutral gray to full vibrancy.
The concept of visual grouping to create boundaries with use of white space or visible elements.
Density-independent pixels (dp)
Flexible units that scale to have uniform dimensions on any screen. They are based on the physical density of the screen. These units are relative to a 160 dpi (dots per inch) screen, on which 1 dp is roughly equal to 1 px.
Display cutout
An area on some devices that extends into the display surface to provide space for front-facing sensors.
The perception of color, or how you would describe the color.
An intent allows an app to signal it needs another app's assistance in performing an action; for example, a messaging app can use the Share intent to share a photo from the Photos app with a contact. Apps can indicate which intents to respond to through activities. Android provides flows and UI for a number of intents. Learn about common intents.
An Android system bar displayed at the bottom of the screen. It allows the user to navigate a device through either a gesture or tapping a button.
Scalable pixels (sp)
Scalable pixels serve the same function as dp, but for fonts. The default value of an sp is the same as the default value for a dp. The Android system calculates the actual font size to use based on the device and the user's preference set in the Settings app of their Android-powered device.
Status bar
An Android system bar displayed at the top of the screen. It contains notification icons and system icons.
A sequence of activities a user follows to accomplish a goal. These activities are arranged in a stack, known as the back stack, in the order in which each activity is opened. Learn more about the back stack lifecycle.
The luminance, or brightness, of a color. Describes the level of light that a digital color value represents.