Seams are edge cuts inserted into a mesh during UV mapping to help it unfold, flattening out into a 2D space for the purpose of texture assignment. This process is achieved in 3D modeling software, but the cuts it makes are highly important for properly unfolding a model and getting it to look as intended inside Unity. An edge is classified as a seam in UV space when it has only one neighboring face, as opposed to two. Essentially, the seams determine how a mesh's UVs are cut apart into separate UV shells or UV islands, which are arranged into a final UV layout. This layout maps a texture onto the mesh surface, as follows:
Always minimize UV seams where feasible by joining together disparate ...