What is the keyboard shortcut used to open the expression panel when clicking the animation stopwatch?

The keyboard shortcut that opens the expression panel when clicking the animation stopwatch in Adobe After Effects is the Alt (Option on Mac) key. When you hold down this key while clicking the stopwatch icon next to a property, it allows you to enter an expression for that property. This feature is essential for advanced animations and effects, enabling users to create dynamic relationships between different properties or employ mathematical operations to modify behaviors.

The Alt or Option key is integral because it signifies that you want to switch from keyframing to using expressions, which can significantly enhance the control and versatility of animations within the software. Using expressions can streamline workflows and enable complex animations that would be tedious or impossible to achieve manually through keyframes alone.