What do I use as an aspect ratio for mobile development?

Title says it all. If there are numerous ones, I would like to know as many as you can think of.

Your content has to adapt to the many aspect ratios on the market. One widely used approach is (using Landscape orientation as an example):

  1. Identify the min and max aspect ratios (typically 4:3 and 19:6)
  2. Design your primary content for 4:3 the min aspect ratio
  3. Fill the remaining 19:6 bleed zone with content that can be cut off ( it will show on wide devices and not show at all on 4:3)
  4. Code your UI layout scheme so that it scales evenly based on the height of the screen. The Unity UI canvas components provide this scaling option.