Why is texture important in painting?

Textures in paintings come from the way you move your brush. Or form the application of the paint (mostly oil based). There are tools used to push the paint around so it seems to extrude off the base of the board or paper.

A Quick Overview -

To achieve the look of texture with watercolour paint, you vary the amount of paint you use as well as adding more paint or ink, after the first or base coat is dry. For example, the bark of a tree - paint the trunk being sure to shade and highlight the surface to achieve a cylindrical look. Once the painting is dry, go back in with both your shade colours and either a white gouache or the edge of a very sharp knife to add the appearance of lifted and roughened areas of the bark.

Texture in oil and acrylic paintings is much easier as the paint can be applied by brush or with a pallet knife to give it actual texture. However, it is essential to use the colours of the paint to achieve the look of texture and use the actual texture of the paint to enhance the effect.

In craft painting and in some specialty painting there are acrylic and polymer mediums that can be used to build up dimensional grounds to achieve texture. These still need to be painted over to give the piece at appearance of reality.

There are also additives and other textural materials (ie. flocking) that can be added to the finished painting to give it "real" texture.