• Each pixel is a small square that shows a single color
• An 800 x 600 image is 800 pixels wide by 600 pixels high, 480,000 pixels in all (0.5 megapixels)
• Digital cameras today produce images with several megapixels per image, say 8000 x 6000 for about 5 megapixels
• If a picture is 1,000 pixels by 2,000 pixels, it has 1,000 x 2,000 = 2 million pixels. We call it a 2 MegaPixel photo ( 2MP) Digital cameras and cell phone cameras are rated in MP or how many pixels they can capture.

• Each pixel represents a single color consisting of the 3 primary colors Red, Green, and Blue (RGB)

So essentially, any color can be encoded as three numbers .. one each for red, green, and blue.

In RGB, a color is defined as a mixture of pure red, green, and blue lights of various strengths. Each of the red, green and blue light levels is encoded as a number in the range 0..255, with 0 meaning zero light and 255 meaning maximum light.

So for example (red=255, green=100, blue=0) is a color where red is maximum, green is medium, and blue is not present at all, resulting in a shade of orange. In this way, specifying the brightness 0..255 for the red, blue, and green color components of the pixel, any color can be formed.

Pigment Note -- you may have mixed color paints, such as adding red and green paint together. That sort of "pigment" color mixing works totally differently from the "light" mixing we have here. Light mixing is, I think, easier to follow, and in any case, is the most common way that computers store and manipulate images.

It's not required that you have an intuition about, say, what blue=137 looks like. You just need to understand that any color can be made by combining the three color values.