CSS3 animations represent a revolutionary feature enabling granular control over element motion through multiple control points. Unlike transitions that respond to state changes, animations operate autonomously, support intricate transformations, and provide extensive playback controls.

Core Implementation Pattern

The animation workflow follows two distinct phases: declaration and application.

/* Phase 1: Declaration */
@keyframes expandElement {
  from {
    width: 80px;
    opacity: 0.3;
  }
  to {
    width: 300px;
    opacity: 1;
  }
}

/* Phase 2: Application */
.animated-box {
  animation-name: expandElement;
  animation-duration: 1.8s;
}

Keyframe Specifications

Animation sequences define intermediate states using percentage notation or keyword aliases (from/to). Each keyframe represents a temporal snapshot where CSS properteis interpolate smoothly between defined values.

.slider {
  width: 120px;
  height: 120px;
  background: linear-gradient(45deg, #ff6b6b, #4ecdc4);
  animation-name: slideRight;
  animation-duration: 3s;
}

@keyframes slideRight {
  0% {
    transform: translateX(0) rotate(0deg);
    border-radius: 0;
  }
  50% {
    transform: translateX(250px) rotate(180deg);
    border-radius: 50%;
  }
  100% {
    transform: translateX(500px) rotate(360deg);
    border-radius: 0;
  }
}

Animation Property Reference

.bouncer {
  width: 100px;
  height: 100px;
  background: #9b59b6;
  animation-name: bounce;
  animation-duration: 2.5s;
  animation-timing-function: cubic-bezier(0.68, -0.55, 0.265, 1.55);
  animation-delay: 1s;
  animation-iteration-count: infinite;
  animation-direction: alternate;
  animation-fill-mode: both;
}

.bouncer:hover {
  animation-play-state: paused;
}

@keyframes bounce {
  0%, 100% { transform: translateY(0) scale(1); }
  50% { transform: translateY(-150px) scale(0.8); }
}

Shorthand Notation

The animation property consolidates multiple declarations into a single statement, excluding animation-play-state.

/* syntax: name duration timing-function delay iteration-count direction fill-mode */
.element {
  animation: pulse 3s ease-in-out 0.5s 4 alternate forwards;
}

@keyframes pulse {
  from {
    box-shadow: 0 0 0 0 rgba(52, 152, 219, 0.7);
  }
  to {
    box-shadow: 0 0 0 40px rgba(52, 152, 219, 0);
  }
}

Key considerations:

• animation-direction: alternate creates back-and-forth motion
• animation-fill-mode: forwards preserves the final keyframe state
• Playback control via animation-play-state is typically used interactively

Timing Function Precision

The animation-timing-function property defines acceleration patterns:

Frame-Based Animation with steps()

The steps() function enables sprite-sheet style animations by dividing the duration into equal intervals.

.typewriter-container {
  width: 0;
  height: 60px;
  overflow: hidden;
  white-space: nowrap;
  border-right: 3px solid #2c3e50;
  animation: typing 5s steps(30) forwards;
}

@keyframes typing {
  from {
    width: 0;
  }
  to {
    width: 450px;
  }
}

This technique creates a typewriter affect where text reveals character-by-character through discrete width increments rather than smooth interpolation.