Pixels are the smallest unit that makes up an image. Pixels are made up of RGB (Red, Green, and Blue) subpixels, and the intensity of each subpixel will decide the final output colors.
So basically, more pixels will make a better-looking and well-defined image.
You may have heard of the term PPI (Pixels Per Inch), which defines the number of pixels that an image or video has per inch of its area.
There is a second important thing, and that is resolution, which gives an idea about an image. A higher-resolution image would have a higher number of pixels, whereas a lower number of pixels would make a lower-resolution image.
Now let’s take an example of a 720p image, which means that the image has 1280 pixels wide and 720 pixels high with an aspect ratio of 16:9.
Here is a chart for better clarity about the resolution
| Resolution | Measurements | Number of pixels in total |
| 480p (SD) | 640 x 480 | 307,000 |
| 720p (HD) | 1280 x 720 | 921,600 |
| 1080p (Full HD) | 1920 x 1080 | 2,073,600 |
| 4K (Ultra HD) | 3840 x 2160 | 8,294,400 |
| 8K (Ultra HD) | 7680 x 4320 | 33,177,600 |
Fun fact: The Human eye has a resolution of about 576 Megapixels.