Packets

• Files that are broken down into smaller parts when sending data across a network.

• Whole files are too large to transfer as one unit so data packets allow data to be transferred across a network quickly.

• Each packet of data is redirected by routers across networks until it arrives at its destination. • Data packets may split up and use alternative routes to reach the destination address. • When all the packets have arrived at the destination address, the data is re-assembled back into the original file.

In the header: - Source Address - Destination Address - Packet Number - Protocol In the payload: - The data itself In the trailer: - A checksum which is a calculation on the data to see if any errors or corruption have occurred during transmission.