What is the meaning of `auto` value in a CSS property.

Question

What is the meaning of auto value of a CSS property. What happens when value of a CSS property is set to auto?

Answer 1

auto means automatically adjusted. The most common reason I use auto is:

margin: 0 auto;

to center an element.

Please note: if size is not declared, then it won't work.

Example 1: div is not centered, auto does not work

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Example 2: div is centered to the page