Raster graphics (also called bitmap graphics) are digital images composed of a grid of pixels, where each pixel contains color information. Unlike vector graphics, raster images have a fixed resolution and become pixelated when enlarged beyond their original size.

Key characteristics:

- Pixel-based: Made of individual colored squares (pixels)

- Fixed resolution: Determined by pixel dimensions

- Photo-realistic: Excellent for photographs and complex images

- File size: Can be large, especially at high resolutions

- Format variety: Many formats available (PNG, JPEG, WebP, etc.)

Raster graphics are ideal for:

- Photographs

- Complex illustrations with gradients

- Detailed artwork

- Textures and patterns

- Screenshots

Common raster file formats:

- PNG (supports transparency)

- JPEG (good compression for photos)

- WebP (modern, efficient format)

- GIF (supports animation)

- BMP (uncompressed)

When working with raster graphics, it's important to use the appropriate resolution for the intended use case to avoid quality issues.