Libian

Libian refers to the gradual, systematic simplification of Chinese character forms during the 2nd century BC, by which the Chinese writing system transitioned from the seal script character forms to clerical script characters during the early Han dynasty period, through the process of making omissions, additions, or transmutations of the graphical form of a character to make it easier to write. Libian was one of two conversion processes towards the new clerical script character forms, with the other being liding, which involved the regularisation and linearisation of character shapes.

Process
The earlier seal script characters were complicated and inconvenient to write; as a result, lower-level officials and clerics gradually simplified the strokes, and transitioned from writing with bowed ink brushes to using straight ink brushes, which both improved ease of writing.

The complexity of characters can be reduced in one of four ways:
 * Modulation : The replacement of character components with an unrelated component. For example, the ancient bronze script form of 'to shoot arrows' was written as 射-bronze.svg, however the left-side component became replaced with  'body' during the transition to clerical script writing.
 * Mutation : Some characters undergo modulation so suddenly that no clue hinting at the original form can be found in the new form. For example, the transition from the seal script character 春-seal.svg 'spring' to the clerical (and by extension, modern) form completely drops any hints of the original  component, instead replacing it with  which seemingly has zero basis in relation to the original component.
 * Omission : The complete omission of a character component. For example, the clerical script form of 'to write' (Old Chinese: *hlja) completely omits the phonetic component  *tjaːʔ at the bottom of the seal script form 書-seal.svg.
 * Reduction : Simplifies character components to a form with fewer strokes. For example, the ancient form of ACC-s05903.svg / *sen 'celestial being' had the complex phonetic component  *sʰen simplified into  *sreːn, creating the clerical form.

One consequence of the libian transition process is that many radicals formed as a result of simplifying complex components within seal script characters—for example, characters containing 'heart' /  on the side had the component simplified into, as seen in  and , and these newly-formed radicals are still used in modern-day Chinese writing as the fundamental basis for constructing and sorting Chinese characters.