Watercolor painting is an art form that creates artistic representations, usually on paper, using pigments that are water-soluble. Other forms of painting use oil soluble paints or dry pigment in sticks such as pastels. Watercolor painting is familiar to most of us as the children's activity performed with boxed sets of color pans; the colored blocks are swiped with a wet brush and the pigment transfers itself to the watered brush and thence to the paper. Adult watercolorists use different paints, however. The children's versions do not contain the amount of pigment needed to achieve the effects available with 'artist grade' watercolor paints.
Watercolor painting employs a type of palette specific to the form - typically a large flat piece of plastic with depressions around the perimeter. Watercolor paint sold in tubes is squeezed into these depressions and allowed to dry. This is the equivalent of the children's set of dried colored cubes. Some artists use 'fresh' watercolor paint directly from the tube and do not allow it to dry. They claim the colors are fresher if the paint is not allowed to dry before it reaches the paper.
Watercolor painting employs a variety of different techniques specific to the medium. The most characteristic is perhaps the technique known as wet-in-wet, in which large portions of the paper are wet, either with an earlier application of a wash of color or with plain uncolored water. The brush is loaded with pigment from the palette and either dropped or stroked onto the paper, allowing the color to flow wherever it will, blooming into interesting and unexpected patterns, merging with previous applications of other colors and forming new shades. Wet-in-wet watercolor painting is difficult to control, but can yield some of the most surprising and satisfying results.
If you are interested in exploring watercolor painting for yourself, treat yourself to truly 'artist grade' tubes of watercolor paint. Most paint manufacturers offer a 'student grade' line that is significantly cheaper, but these paints will not produce the same results, which can be disheartening to the beginner. Rather than buying a more complete palette of cheaper paints, purchase a smaller number of the higher quality paints, since almost any shade can be created from mixing together two or more other colors. For instance, you can mix a truly dark black shade by blending red and green pigments, so most watercolorists don't even keep a tube of black watercolor paint in their paint box.