Textures are images, and therefore 2D planes, whilst most 3D models are...er... 3D. A UV map serves to correspond the 2D to the 3D (Figure 1).

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Figure 1. UV maps introduced

The UV map of a table is shown in Figure 2. Tables are regular objects, and are therefore retentively easy to UV map. A less regular object, such as a skull, can be more complex (Figure 3).

Figure 2. The UV map of a table

Figure 3. The UV map of a skull

Seams and islands

Look at the clothes you are wearing. They will feature seams. Cut the clothes along the seams and you will be left with many pieces of flat fabric (Figure 4). The seams of a UV map are no different.

Figure 4. The seams of clothes

The seams of a UV map define UV islands. The seams of the skull UV map of Figure 3 are shown in Figure 5. The seams are highlighted is red, whilst the islands are shown in green.

Figure 5. Seams (red) and islands (green)