Keyframes are used to set parameters for motion, effects, audio, and many other properties, usually changing them over time. A keyframe marks the point in time where you specify a value for a layer property, such as spatial position, opacity, or audio volume. Values between keyframes are interpolated. When you use keyframes to create a change over time, you typically use at least two keyframes—one for the state at the beginning of the change, and one for the new state at the end of the change.

When the stopwatch is active for a specific property, After Effects automatically sets or changes a keyframe for the property at the current time whenever you change the property value. When the stopwatch is inactive for a property, the property has no keyframes. If you change the value for a layer property while the stopwatch is inactive, that value remains the same for the duration of the layer.

Set or add keyframes

When the stopwatch is active for a specific property, After Effects automatically adds or changes a keyframe for the property at the current time whenever you change the property value.

To activate the stopwatch and enable keyframing, do one of the following

• Click the Stopwatch icon next to the property name to activate it. After Effects creates a keyframe at the current time for that property value.
• Choose Animation > Add [x] Keyframe, where [x] is the name of the property you are animating.

Add a keyframe without changing a value

Auto-keyframe mode

To turn auto-keyframe mode on, choose Enable Auto-keyframe from the Timeline panel menu. When Auto-keyframe mode is enabled, modifying a property automatically activates its stopwatch and adds a keyframe at the current time.

Auto-keyframe mode is off by default. When Auto-keyframe mode is off, modifying properties and animating with keyframes behave as in previous versions of After Effects.

Move the current-time indicator (CTI) to a keyframe

After you set the initial keyframe for a property, After Effects displays the keyframe navigator. You can use the keyframe navigator to move from keyframe to keyframe or to set or remove keyframes. When the keyframe navigator box is filled with a diamond, the current-time indicator lies precisely at a keyframe for that layer property. When the keyframe navigator box is not filled , the current-time indicator lies between keyframes.

• To move to the next or previous keyframe, click a keyframe navigator arrow.
• To snap to a keyframe or marker, Shift-drag the current-time indicator.
• To move to the next or previous visible item in the time ruler (keyframe, marker, or work area end), press K or J.

For instructions for moving the current-time indicator to other elements and times, see Move the current-time indicator (CTI).

Select keyframes

In layer bar mode, selected keyframes are blue. Unselected keyframes are gray.

In Graph Editor mode, the appearance of a keyframe icon depends on whether the keyframe is selected, unselected, or semi-selected (another keyframe in the same property is selected). Selected keyframes are solid yellow. Unselected keyframes retain the color of their corresponding graph. Semi-selected keyframes are represented by a hollow yellow box.

• To select a keyframe, click the keyframe icon.
• To select multiple keyframes, Shift-click the keyframes or drag a marquee (selection box) around the keyframes. If a keyframe is selected, Shift-clicking it deselects it; Shift-dragging to draw a marquee around selected keyframes deselects them.

• To select all keyframes for a layer property, Alt-click (Windows) or Option-click (Mac OS) a segment between two keyframes in the Graph Editor, or click the layer property name in the layer outline.
• To select all keyframes for a property that have the same value, right-click (Windows) or Control-click (Mac OS) a keyframe, and choose Select Equal Keyframes.
• To select all keyframes that follow or precede a selected keyframe, right-click (Windows) or Control-click (Mac OS) a keyframe, and choose Select Previous Keyframes or Select Following Keyframes.

Keyframe menu commands

When you select one or more keyframes, the keyframe menu becomes available at the bottom of the Graph Editor.

Displays the value of the selected keyframe. If more than one keyframe is selected, the Display Value command is available, which displays the value of the highlighted keyframe in the selection.

Opens a dialog box in which you can edit the value of the keyframe.

Selects all keyframes in a property that have the same value.

Selects all keyframes preceding the currently selected keyframe.

Selects all keyframes following the currently selected keyframe.

Holds the property value at the value of the current keyframe until the next keyframe is reached.

Opens the Keyframe Interpolation dialog box.

Toggles Rove Across Time for spatial properties.

Opens the Keyframe Velocity dialog box.

Opens a submenu with the following options:

Analyzes amplitude within the composition work area and creates keyframes to represent the audio.

Analyzes the current expression and creates keyframes to represent the property values it describes.

Automatically adjusts the influence into and out of a keyframe to smooth out sudden changes.

Automatically adjusts the influence into a keyframe.

Automatically adjusts the influence out of a keyframe.

Converts the rate of change in scale from linear to exponential.

Imports RPF camera data from third-party 3D modeling applications.

Opens the Sequence Layers assistant.

Reverses selected keyframes in time.

Delete or disable keyframes

• To delete any number of keyframes, select them, and then press the Delete key.
• To delete one keyframe in the Graph Editor, Ctrl-click (Windows) or Command-click (Mac OS) a keyframe with the Selection tool.
• To delete all keyframes for one layer property, click the stopwatch button to the left of the name of the layer property to deactivate it.

  When you click the stopwatch button to deactivate it, keyframes for that property are permanently removed and the value of that property becomes the value at the current time. You cannot restore deleted keyframes by clicking the stopwatch button again. Deleting all keyframes does not delete or disable expressions.

• To temporarily disable keyframes for a property, add an expression that sets the property to a constant value. For example, you can add this very simple expression to the Opacity property to set it to 100%: 100.

If you accidentally delete keyframes, choose Edit > Undo.

Jeff Almasol provides a script on his redefinery website that automatically removes keyframes based on specified criteria—for example, all keyframes in the work area, all odd-numbered keyframes.