Abstract

The evolution of 2D animation traces a journey from hand-flipped pages to computer-based tools. Starting with simple flipbooks in the 19th century, the medium advanced through cel animation in the 20th century to digital workstations and software in the 21st. This article explains key terminology and historical developments in plain language, aimed at high school students interested in university animation programs.

Keywords
2D animation, flipbook, cel animation, digital animation, animation history, keyframe.

A flipbook is a small booklet with a sequence of images printed on its pages. When you flip the pages quickly, the images appear to move. In what is called the kineograph, or early flipbook, an 1868 British patent by John Barnes Linnett described a device where a horse appeared to gallop when the pages were turned. (Flipsnack Blog)

Flipbooks show the basic principle of animation: the “illusion of motion.” If each image changes slightly from the previous one, and they are shown in rapid succession, the brain interprets movement.

In the late 19th and early 20th centuries the idea of making drawings move was pioneered using devices such as the zoetrope and phenakistoscope. (Fiveable) These devices were simple: drawings or pictures placed in a drum or around a disc, spun, and viewed through slits to create motion. They were pre-cinematic experiments.

The age of drawn film and cel animation

As film technology emerged, animators moved from mechanical toys to cinema. The term “traditional animation” (also called cel animation) describes the method where each frame is hand-drawn or inked onto transparent sheets called cels (short for “celluloid”). (StudioBinder)

In this process:

  • The background is drawn or painted once.
  • On transparent cels artists draw characters or moving parts.
  • The cels are placed over the background and photographed one frame at a time.

This allowed only the moving elements to be redrawn, saving effort compared with redrawing the entire scene each frame. (Wikipedia)

One landmark was the 1937 American film Snow White and the Seven Dwarfs, considered the first full-length animated feature produced mainly using the cel process. (adobe.com) Technically, the animator would draw key frames (major poses) and in-between frames (transitions) in a process called “in-betweening”. The term “keyframe” refers to the main drawings that define the movement, and “in-betweens” fill the gaps.

Another key term is “frame rate,” which refers to how many individual frames are shown per second. Traditional animated films typically used 24 frames per second (fps) for smooth motion. (StudioBinder)

Terminology you might hear

  • Keyframe: A drawing that shows a principal position in the movement (for example, a character’s arm fully raised).
  • In-between: The drawings between keyframes that smooth the motion.
  • Frame rate: Number of still images shown each second; higher rates usually result in smoother movement.
  • Cel: Transparent sheet on which animators draw or paint characters or moving elements, which are then layered over backgrounds. (Wikipedia)
  • Background: Static artwork that appears behind moving characters or objects.
  • Animation camera or rostrum camera: A camera set-up that films each cel or background layer frame-by-frame.
  • Traditional animation / hand-drawn animation: The process of drawing each frame by hand, often using cels. (Baianat)

Transition to digital tools

By the late 20th century animators began to use computers. The process of digital ink and paint replaced many physical cels. (adobe.com) Software was developed to assist frame-by-frame drawing, digital colouring and layering. For example, the software DigiCel FlipBook was released in 1999 to replicate the traditional process on computer. (Wikipedia)
Another tool, Toonz (later open-source “OpenToonz”), provided modules for scanning drawings, cleaning up lines, and digital colouring. (Wikipedia)

Digital animation offers advantages: faster colouring, easier revision, digital storage, and workflows that allow smaller teams. However, the principles of timing, spacing, keyframes and in-betweens remain central.

Why this evolution matters for a university-bound animation student

If you are exploring animation study, knowing this evolution helps you understand where you will start and where tools are headed. Beginners often start with pencil & paper exercises, learning keyframes and in-betweening before moving to software. Software training might include learning how to set timing charts, clean up drawings, and composite layers digitally.

Studios still value the foundational knowledge of hand-drawn animation even when production is digital. According to educational blogs, the hand-drawn process develops understanding of movement that simply using automated tools cannot replace. (prolificstudio.co)

How you can explore this yourself

Start with a simple flipbook exercise: draw a ball bouncing across a few pages, flip quickly and observe how your brain sees movement. Then try a frame-by-frame exercise: draw a character waving in keyframes and fill the in-between frames. Notice how timing (speed of motion) and spacing (the size or distance of change between frames) affect how “slow” or “fast” the action feels.

Then explore software: many introductory programs allow digital drawing of keyframes and in-betweens, layering of backgrounds and characters, and simple playback. Learning to move between hand-sketch and digital tools gives a strong skill set.

Summary of phases

  1. Flipbooks and optical toys (19th century): early experiments in motion illusion.
  2. Hand-drawn traditional/cel animation (early to mid-20th century): frames drawn on cels, layered over backgrounds, photographed.
  3. Digital 2D animation (late 20th century to present): software tools that replicate or extend traditional processes with digital workflows.

Understanding this path gives insight into how the craft has changed and how the same basic principles of animation still hold true today. If you plan to study 2D animation at university you will likely explore all three, developing both hand-drawn skills and digital tool proficiency.