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To begin our explorations, let's look at an example from the Internet Relay Chat (IRC) protocol. The following string represents the command that you'd send to an IRC server to post a message to a particular channel:

"PRIVMSG #practicing-ruby-testing :Seasons greetings to you all!\r\n"

Even if you've never used IRC before or looked into its implementation details, you can extract a great deal of meaning from this single line of text. The structure is very simple, so it's fairly obvious that PRIVMSG represents a command, #practicing-ruby-testing represents the channel, and that the message to be delivered is "Seasons greetings to you all!". If I asked you to parse this string to produce the following array, you probably would have no trouble doing so without any further instruction:

["PRIVMSG", "#practicing-ruby-testing", "Seasons greetings to you all!"]

But if this were a real project and not just an academic exercise, you might start to wonder more about the nuances of the protocol. Here are a few questions that might come up after a few minutes of careful thought:

• What is the significance of the : character? Does it always signify the start of the message contents, or does it mean something else?

• Why does the message end in \r\n? Can messages contain newlines, and if so, should they be represented as \n or \r\n, or something else entirely?

• Will messages always take the form "PRIVMSG #channelname :Message Body\r\n", or are their cases where additional information will be provided?

• Can channel names include spaces? How about : characters?

Try as we might, no amount of analyzing this single example will answer these questions for us. That leads us to a very important point: Understanding the meaning of a message doesn't necessarily mean that we know how to process the information contained within it.