🖥 Bottom sheets is basically a slide up from the bottom of the screen to reveal more content.You can find more detailed information of Bottom Sheet on Google Material Design guidelines. https://material.io/guidelines/components/bottom-sheets.html
1). Persistent Bottom Sheet.
2). Modal Bottom Sheet.
Persistent bottom sheets display in-app content that supplements the main view. It remains visible even when not actively in use, resting at the same elevation as an app and integrating with its content.
Modal bottom sheets are alternatives to menus, or simple dialogs, and can display deep-linked content from another app. They appear above other UI elements and must be dismissed in order to interact with the underlying content. When a modal bottom sheet slides into the screen, the rest of the screen dims, giving focus to the bottom sheet.
Here few important attributes has to observed.
app:layout_behavior: This attribute makes the layout act as bottom sheet. The value should be android.support.design.widget.BottomSheetBehavior
app:behavior_peekHeight: This is the height of the bottom sheet when it is minimized.
app:behavior_hideable: Makes bottom sheet hidden when swiped it down.