Glossary
Quick definitions for display and screen terminology used across ScreenRes.tools.
A
Anti-aliasing
A technique that smooths jagged edges on text and graphics by blending edge pixels with surrounding colors.
Aspect Ratio
The proportional relationship between a display's width and height, such as 16:9 or 4:3.
B
C
CLS
Cumulative Layout Shift — a Core Web Vital that measures how much page content unexpectedly moves during loading.
Color Depth
The number of bits used to represent each pixel's color. 8-bit = 256 shades per channel; 10-bit = 1024.
Contrast Ratio
The difference in luminance between the brightest white and darkest black a display can produce, e.g. 1000:1.
CSS Pixel
A logical unit used by browsers for layout. One CSS pixel may map to multiple device (hardware) pixels on HiDPI screens.
D
Dead Pixel
A pixel that remains permanently off (black) regardless of the image displayed, caused by a transistor failure.
Device Pixel
A single physical light-emitting element on the display hardware. Also called a hardware pixel.
DPI
Dots Per Inch — the number of individual dots a device can place within one inch. Often used interchangeably with PPI for screens.
DPR
Device Pixel Ratio — the ratio of physical pixels to CSS pixels. A DPR of 2 means each CSS pixel maps to a 2×2 grid of hardware pixels.
F
Frame Delta
The time in milliseconds between two consecutive frames rendered by the display. Lower = smoother motion.
G
Gamut
The complete range of colors a display can reproduce. Wider gamuts (like DCI-P3) show more vivid colors than sRGB.
Ghosting
A trail or shadow left behind fast-moving objects on screen, caused by slow pixel response times.
H
Hz
Hertz — the unit measuring how many times per second the display refreshes its image. 60 Hz = 60 refreshes/second.
I
IPS Glow
A faint warm glow visible at wide viewing angles on IPS panel displays, especially noticeable in dark scenes.
N
Nit
A unit of luminance (cd/m²) measuring how bright a display can get. Typical laptops range from 250–500 nits.
P
PPI
Pixels Per Inch — the density of pixels on a display. Higher PPI means sharper text and images at the same viewing distance.
R
Refresh Rate
How many times per second the display updates the image shown. Higher refresh rates (120 Hz, 144 Hz) produce smoother motion.
Resolution
The total number of pixels a display can show, expressed as width × height (e.g. 1920×1080).
Response Time
The time it takes for a pixel to change from one color to another, typically measured in milliseconds (ms). Lower is better for fast content.
S
sRGB
Standard Red Green Blue — the most common color space for web content and consumer displays.
Stuck Pixel
A pixel that stays permanently lit in one color (red, green, or blue) instead of changing with the rest of the image.
Sub-pixel
The individual red, green, and blue elements that make up a single pixel. Sub-pixel rendering uses these to improve text sharpness.
V
Viewport
The visible area of a web page in the browser window. On mobile, it can differ from the device's physical screen size.