To activate it, click the Stopwatch symbol next to the property name. For that property value, After Effects creates a keyframe at the current time.
Select Animation > Add [x] Keyframe, where [x] represents the name of the property you want to animate.
Select Insert > Timeline > Frame to add a new frame (F5). Insert > Timeline > Keyframe (F6) or right-click (Windows) or Control-click (Macintosh) the frame where you want to insert a keyframe and pick Insert Keyframe from the context menu to create a keyframe.
In animation and cinematography, a key frame (or keyframe) is a graphic or shot that marks the beginning and finish locations of any seamless transition. Because their position in time is measured in frames on a strip of film or on a digital video editing timeline, these are referred to as frames.
On the timeline, you can lengthen or shorten the time for the specified period. Select the frame span and move the right-side edge of the selected span forward or backward on the timeline. The frames inside the timeline are automatically modified.
The most basic method of animating an item is keyframing. Based on the idea that an item has a starting state or condition that will change over time in terms of location, form, colour, luminosity, or any other property to a new final form.