Can someone explain how auto and inherit values work

[damon2003]

When you use auto for margins for a container, the container is centered, why is this?

thanks,

[David Harrison]

Read the spec:If both 'margin-left' and 'margin-right' are 'auto', their used values are equal. This horizontally centers the element with respect to the edges of the containing block.The whole of section 10.3 is given over to "calculating widths and margins".