Retopology creates a new surface over an existing shape so its edge flow and density better fit a downstream task.

Creates
New connectivity
Preserves
Reference shape
Common use
Animation and games
Often followed by
Texture baking

Retopology versus remeshing

Retopology prioritizes intentional edge flow. Remeshing usually redistributes surface elements more automatically. Decimation primarily removes faces while approximating shape.

Plan for attribute transfer

A new topology usually means new UVs. Bake or project base color, normal, roughness, and metallic data from the generated source onto the optimized mesh.