Access the Particle System from the Animation system

All particleA small, simple image or mesh that is emitted by a particle system. A particle system can display and move particles in great numbers to represent a fluid or amorphous entity. The effect of all the particles together creates the impression of the complete entity, such as smoke. More info
See in Glossary properties are accessible by the Animation system, meaning you can keyframeA frame that marks the start or end point of a transition in an animation. Frames in between the keyframes are called inbetweens.
See in Glossary them in and control them from your animations.

To access the Particle SystemA component that simulates fluid entities such as liquids, clouds and flames by generating and animating large numbers of small 2D images in the scene. More info
See in Glossary’s properties, follow these steps:

1. Attach an Animator componentA component on a model that animates that model using the Animation system. The component has a reference to an Animator Controller asset that controls the animation. More info
   See in Glossary to the Particle System’s GameObjectThe fundamental object in Unity scenes, which can represent characters, props, scenery, cameras, waypoints, and more. A GameObject’s functionality is defined by the Components attached to it. More info
   See in Glossary. An Animation Controller and an Animation are also required.
2. To animate a Particle System property, open the Animation Window with the GameObject containing the Animator and Particle System selected. Click Add Property to add properties.
3. Scroll to the right to reveal the add controls.

Note that for curves, you can only keyframe the overall curve multiplier, which can be found next to the curve editor in the InspectorA Unity window that displays information about the currently selected GameObject, asset or project settings, allowing you to inspect and edit the values. More info
See in Glossary.