Bit depth (also called color depth) refers to the number of bits used to store color information per pixel per channel. 8-bit per channel (the JPEG standard) allows 256 possible values per channel — 256³ = 16.7 million possible colors. 16-bit per channel allows 65,536 values per channel — over 280 trillion possible colors. Higher bit depth means smoother gradients and more precise color representation.
For most consumer photography, 8-bit is sufficient — human eyes can't distinguish more than approximately 10 million colors. Where higher bit depth matters: gradient smoothness in sky and skin tone photographs (16-bit avoids visible color banding called "posterization"), HDR photography and video (10-bit minimum for HDR content), and professional color grading workflows where multiple adjustments compound precision errors.
Format bit depth support: JPEG is 8-bit only. PNG supports 8-bit and 16-bit (PNG-16). TIFF supports 8, 16, and 32-bit. WebP and AVIF support 10-bit and 12-bit. RAW camera files are typically 12-14 bit. For web distribution, 8-bit is standard and sufficient. 16-bit only matters for archiving source files or professional post-production workflows.