At its most basic, Paint Effects is a traditional paint program that you can use to put paint on a 2D canvas. Paint Effects has many traditional preset brushes to choose from, including airbrushes, felt-tipped markers, oils, pastels, pencils, pens, and watercolors. They work like paintbrushes, leaving paint on the canvas along the stroke path.
When you paint with brushes that use tubes, paint appears to sprout from the stroke you draw, like plants growing from seeds. You can define how the tubes sprout to achieve very complex results with a single brush stroke.
You can use the provided preset brushes, or create your own custom brushes to paint images and textures.