Various tools can be used to paint directly to the image. Other tools effectively do this but tend to be placed in another category, as well.

The PSP help file includes the eraser, which makes sense as a 'painting tool'. It also groups in the tubes, which are included elsewhere, for purposes here. I add the dropper, though it doesn't paint itself - it does 'load up' the brushes with colors to be used.

These options are available for all but Flood and the Eye Dropper (though Hardness and Opacity are unavailable for Eraser). Each group of settings is kept or saved for each of the tools. So the airbrush might use one hardness and size, and the clone might use another, and so on.

 
• Hardness: softens the edges - feathering. In the example, the hardness is all the way down to 38, and the brush looks almost like a sphere. Lots of feathering.
   
• Opacity: doesn't show in the little picture of the brush. But an opacity down around 50% will give a light touch brush, with a lot of the underlying image showing through.
   
• Size: larger or smaller diameter brush
   
• Step: how often the brush is 'stamped' as you trace out a path. 1 or 2 would make for a smooth brush.
   
• Density: how tightly packed are the 'bristles'. Here it's 100%, and the brush looks like a solid ball.
   
• Shape: a round brush, but also square, and as slanted lines.
   
• Build up: check box in order to build up, darken, the brush strokes by painting over them. Not available for all tools.
   
• Brush icon (upper right): the brush styles. There's the Normal style. There's a custom shape catalog. And then there are textured brushes, fairly similar, but different enough in effect.

Brush:

The brush, using the settings above. Not so different from air brush, just below, but the build-up option can be used for the brush.

Air Brush:

Very much like the brush, above.

Clone:

Right click in the image, or in another image, and left click somewhere else, or in another image. In the new area, a copy is made of what would be at the cursor if it were still over being right clicked.