WEB design: The difference between pt and px text sizes in CSS

In web design CSS, fonts are often used, and the setting unit of font size is commonly used in two kinds: px and pt. What's the difference between these two?

First understand the basic concept: px is the pixel, pixel, is the most basic point on the screen to display data; The pt is point, a common unit in the printing industry, equal to 1/72 inch.

This makes it clear that px is a point, it is not a unit of length in nature, who can tell how long and how big a "point" is? It can be very small or very large. If the dot is small, the picture is clear, we call it "high resolution", on the contrary, it is "low resolution". Therefore, the size of the "point" will "change", also known as the "relative length".