The ease-in and ease-out are timing functions in CSS used to control the speed of a CSS animation or transition over time. They define the rate of change of the animation, determining how quickly or slowly it accelerates or decelerates. Both ease-in and ease-out are variations of the more general ease timing function.

Syntax:

// The ease-in timing function
.element {  
     transition: property-name duration ease-in;
}

// The ease-out timing function
.element {   
      transition: property-name duration ease-out; 
} 

// The ease timing function
.element 
{  
      transition: property-name duration ease; 
} 

ease-in:

• The ease-in timing function starts the animation slowly and gradually accelerates toward the end.
• The initial phase of the animation is slower, providing a smooth and gentle start.

ease-out:

• The ease-out timing function starts the animation quickly and decelerates toward the end.
• The initial phase of the animation is faster, and it slows down as it progresses, giving a smooth and gentle finish.

ease:

• The ease timing function is a combination of ease-in and ease-out.
• It starts slow, accelerates in the middle, and then decelerates towards the end, providing a balanced and natural feel.