What makes Composition with Yellow, Blue and Red an example of neoplasticism?

Composition with Yellow, Blue and Red is a quintessential example of Neoplasticism because it adheres to Piet Mondrian’s strict formal program, which sought to express a "pure" reality through nonrepresentational means.1

The work exemplifies this style through several key characteristics:

• Reduction to Basic Elements: Mondrian eliminated all imagery from the external, recognizable world, restricting his visual language to straight vertical and horizontal lines that form a grid, and the use of primary colors (red, yellow, and blue) alongside neutrals.123
• Plastic Expression: Rather than depicting nature, the painting uses these fundamental elements to achieve "plastic expression." The four discrete areas of primary color are carefully "weighted" to act as a counterbalance to the lines, creating a sense of equilibrium and harmony.12
• Abstract Order: The composition is derived from abstract rules of geometry and color rather than fragments of nature. This approach reflects Mondrian’s goal of rendering a "true vision of reality" that conveys a sense of universal order and spiritual clarity.23

By mobilizing line, form, and hue to serve these ends, the painting embodies the core tenets of the De Stijl movement.12