Lazard's universal ring

Lazard's universal ring, denoted as \( L \), is a fundamental construction in algebraic topology, specifically in the context of homotopy theory and stable homotopy categories. It is a ring that encodes information about stable homotopy groups of based topological spaces. More formally, Lazard's universal ring can be thought of as a certain commutative ring that classifies vector bundles over spheres and, by extension, stable homotopy types of spaces.