How can carbon paper copy writing without a scanner?

Before digital copying, a person could write a note and make another copy underneath at the same time. Carbon paper placed a transferable dark coating between the top writing sheet and a second sheet below.

A pen or typewriter pressed on the top sheet. At each pressed spot, some coating moved from the carbon paper onto the lower sheet. The moving pressure traced the same path as the original writing, so the lower marks followed the same letters.

The coated side had to face the sheet receiving the copy. Writing on top did not send ink magically through the pages. Two separate things made the records: the pen marked the upper sheet, while pressure transferred pigment to the lower one.

Extra layers could make more copies, though lower impressions could become faint as pressure spread. Carbon copying captured the action of writing, not the meaning of the words. A physical trace of one action became several records.