Simple, intuitive user interface--every feature and user interface element was designed to be immediately intuitive and/or quickly learnable without assistance. It is also designed to be immediately familiar to users of Paint and Photoshop.
Layers--This allows you to compose one complete image from a stack of other images that are blended together.
Unlimited History--Every action you take on an image is recorded in the History window, and is only limited by available disk space and memory.
Support for many popular file formats--The following file formats are supported: PNG, JPEG, BMP, GIF, TGA, DDS, and TIFF. The native Paint.NET image type is PDN which preserves layering.
Download Paint.net here | Paint.net tutorial forums here | Online manual here.
Effects and Adjustments--You can apply many special effects to your image, and support for image adjustments is also possible.
Full Support for Dual- and Quad-Core CPU's, and 64-bit--Paint.NET is fully optimized for the latest in processor technology enabling dramatic performance improvements and the ability to work with larger and more images.
Tablet PC Support--The Paintbrush tool supports the Tablet PC's pressure-sensitivity feature, allowing you to draw in a more natural and artistic manner.
Extensibility--Paint.NET supports plugins that add new effects, adjustments, and file format support.
Free-Paint.NET is provided for no cost with generous licensing terms.