Texturing refers to the act of producing 2d images for use with 3d models. Commonly referred to as "maps" or "skins".
Textures work in conjunction with Shaders and Materials to produce the final rendering. The game model needs Texture Coordinates to wrap the texture onto the model. Multiple Texture Types are often used to control different parts of the shader, such as Normal map or Specular color map.
A variety of techniques and Tools are used to make textures: painting by hand in a traditional 2d package, photo-manipulation, 3d scanning with a photogrammetric tool, painting in 3d directly on models, creating procedurally in a node-based material editor, baking image data from one model to another, etc. some of the best 3d texture Painting software’s are Blender, Substance Painter, ZBrush, Mari, Mud box, 3D coat, Body paint 3D