What is an Alpha Channel? (And Why JPGs Can't Be Transparent)
DefinitionThe data layer in an image that controls transparency.
1The Simple Explanation
Digital images are usually made of Red, Green, and Blue (RGB) channels. An Alpha Channel is a fourth channel that says 'how invisible' a pixel is. Without it, your image is just a rectangle.
2Technical Deep Dive
Stored as an extra 8-bits per pixel in 32-bit images (RGBA). Supports 256 levels of transparency, allowing for smooth shadows and glass effects. Supported by PNG, WebP, TIFF, AVIF, and HEIC.
Common Misconceptions
Myth: All images can be transparent. Fact: JPG does not support alpha channels. If you save a transparent logo as JPG, the background becomes white permanently.