Term: packet

The term packet is typically used in reference to communications – or, more specifically, data transfer. At it’s simplest, a packet is nothing more than some number of bytes of data communicated from one point to another, as a single entity.

The best example might be the transfer of a large file of, say, many megabytes. Rather than just sending the data as one long transmission of data, it’s broken into packets of smaller size. Each packet must be acknowledged by the recipient, or it will be re-sent until it is (or until some limit is exceeded).

As an oversimplification, a file transmission might conceptually look like this:

Here's file "a.jpg" --->

<--- I'm ready for file "a.jpg"

Here's a packet of data -->

<-- I got the packet of data

*** repeat send & acknowledgement many times ***

Here's a packet of data -->

<-- I got the packet of data

That was the last packet of data -->

<-- OK, we're done.

Breaking larger communications into streams of packets allows errors to be tolerated by retransmitting the smaller missed or erroneous packets, rather than having to retransmit the entire file.

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