How are pixels measured?

Related questions

1. How many pixels is 20 megapixels?
2. What is the pixel size for 25 KB?
3. What is 4k resolution in pixels?
4. What shape are pixels?
5. Does retargeting really work?
6. What is Google pixel?
7. Is 1920x1080 resolution 4k?
8. Is more pixels better?
9. Do I need multiple Facebook pixels?
10. Is a 20 megapixel camera good?

Tags

1. #screen
2. #dimension
3. #which
4. #refers
5. #pixels
6. #density
7. #present
8. #height
9. #found
10. #width
11. #number
12. #device
13. #resolution
14. #display
15. #displayed
16. #usually
17. #pixel
18. #measured