UV mapping is the 3D modeling process of projecting a 2D image to a 3D model’s surface for texture mapping.
this process is necessary for proper 3d texture painting, baking textures and applying pbr textures to a model.
UV mapping is a critical element used to map textures on a 3d model.
in blender to correctly uv map any object you start by unwrapping the model which is the process of mapping the 3d vertices of a model in 3d space to a 2d space for textures.
unwrapping in blender starts by adding seams, which are lines or a path of edges on a model to tell blender how the model is going to be flattened or unwrapped, by default seams are given an orange outline in the 3dview and a only viewable in edit mode of a mesh.
Uv unwrapping only works on meshes so other types of objects like curves and nurbs don’t have unwrapping options.