Read dark-to-bright from left to right
Histogram bins on the left represent darker sampled values; bins on the right represent brighter values. The height shows how many sampled pixels fall into each range.
Start with luminance
A luminance histogram is often easier to interpret for exposure than separate RGB channels. RGB channel spikes can still reveal channel-specific clipping or a strong color cast.
Clipping is context-dependent
Near-black or near-white pixels may indicate lost detail, but pure backgrounds, specular highlights, silhouettes, and artistic choices can make clipping intentional.
Compare edits with the same scene
Histograms are particularly useful for comparing exposure, contrast, and tone edits on the same image because the content itself stays constant.