What is android:weightSum in android, and how does it work?

Question

I want to know: What is android:weightSum and layout weight, and how do they work?

Answer 1

From developer documentation

This can be used for instance to give a single child 50% of the total available space by giving it a layout_weight of 0.5 and setting the weightSum to 1.0.

Addition to @Shubhayu answer

rest 3/5 can be used for other child layouts which really doesn't need any specific portion of containing layout.

this is potential use of android:weightSum property.