Pixel is short for picture element and is the term used for each of the small dots of colour on a computer screen which make up a picture. It also refers to the small receivers on IP camera sensors which transfer the light recieved into data.
Each pixel has a colour value of red, green and blue. Varying the values of these three colours will alter the overall colour of the pixel. With IP cameras, the sensor records the red, green and blue values for each of these pixels and then transmits the values to your computer, which then rebuilds them in an image on your screen.
The word is a combination of picture and element, via pix. Pix was first coined in 1932 in a variety magazine headline, as an abbreviation for the word pictures, in reference to movies. By 1938, "pix" was being used in reference to still pictures by photojournalists.
A pixel does not need to be rendered as a small square. This image shows alternative ways of reconstructing an image from a set of pixel values, using dots, lines, or smooth filtering.
A pixel is generally thought of as the smallest single component of a digital image. The definition is highly context-sensitive. For example, there can be "printed pixels" in a page, or pixels carried by electronic signals, or represented by digital values, or pixels on a display device, or pixels in a digital camera (photosensor elements). This list is not exhaustive, and depending on context, there are several terms that are synonymous in particular contexts, such as pel, sample, byte, bit, dot, spot, etc. The term "pixels" can be used in the abstract, or as a unit of measure, in particular when using pixels as a measure of resolution, such as: 2400 pixels per inch, 640 pixels per line, or spaced 10 pixels apart.
This technology is a boon as it has made the work of many technicians easier.