Without context, the question is a bit vague and I may not give the best answer, but in general terms, I would say the answer is a Network Interface Card (NIC) or an Ethernet card.
An Ethernet card is one of a network adapter. It is a physical expansion card that inserts into the PCI expansion slot on a PC and is used to transmit data from the network into the computer. It is connected to the computer using an Ethernet cable.
The Merge Field is a placeholder that holds the variable data that will be inserted into the main document during a mail merge procedure. The columns in a document may represent the categories of information. The Rows represent the records of the different columns. The computer counts a row of data to be a single record.
