An inkpad is a small box that contains a pad of cloth or other material. It is impregnated with ink (the pad is inky). A marker is pressed onto the pad, then onto paper. Any raised marks on the pad leave an impression in ink on the paper.
Ink pads are used with rubber stamps. On the stamp is the symbol of an organisation, for example. After a form has been passed by an official, it is stamped to show it is authentic. Another variation is a date stamp, placed on all letters which arrive in the building. Another version is a stamp with a facsimile (copy) of an official's signature. Using this, staff can send out letters when the official is not present. Rubber stamps and ink pads have been used for at least a hundred years by civil servants and businesses. They are still in use in many countries, but are gradually being replaced with other systems.