A copier, or photocopier, works by using a combination of light, static electricity, and toner to create a duplicate of a printed document. Here are the basic steps involved:

1. The original document is placed on the glass surface of the copier.

2. A bright light shines onto the document, which reflects the light onto a photoconductive drum inside the copier.

3. The light causes the photoconductive drum to become charged with static electricity.

4. The charged areas of the drum then attract toner particles from a rotating drum inside the copier.

5. The toner particles are transferred from the rotating drum to the paper, which is fed through the copier.

6. The toner is then fused onto the paper with heat, creating a permanent image that is an exact copy of the original document.

7. The finished copy is ejected into a tray, where it can be collected by the user.

This process happens very quickly and can produce multiple copies of a document in a short amount of time. More advanced copiers may also include features like automatic document feeders and collating, which can make copying large documents or multi-page presentations much easier.