Packets are small units of data that are transmitted over a network. When information, such as an email or a video, is sent from one computer to another, it is broken down into these packets. Each packet contains a portion of the data, along with important information like the sender's and receiver's addresses, which helps ensure that the data reaches its destination correctly. Once the packets arrive at their destination, they are reassembled in the correct order to recreate the original message. This method of data transmission is efficient and allows for faster communication over networks like the Internet. Packets can also be rerouted if there are issues along the way, enhancing reliability.