Resolution describes the number of pixels in a video image or display, usually expressed as width and height. The source, decoded image and television panel can have different resolutions. More pixels can preserve more detail when the production contains it, but resolution alone does not describe compression quality, motion handling or the condition of the source.
A practical example
A 4K television can show a lower-resolution programme by scaling it to fill the panel. The screen continues using its physical pixels, but that scaling does not turn the original production into a genuinely more detailed 4K source.
A common misunderstanding
Do not infer source resolution from the television's specification, a channel group name or a large player window. Inspect actual stream information where the player makes it available.
Related terms
Stable technical definition. Editorial approach