What it should be:

• Collaborative
• Structured
• Force multiplier

What it should not be:

• A seminar
• Rigidly defined
• A place to check out

The basics

Non of these rules should be set in stone, but there needs to be some structure to ensure this is a productive use of time.

• Use one keyboard and screen

• Use a private room

• Keep time and rotate who is on the keyboard every 10 to 15 minutes.

• Everyone gets time at the keyboard, even non-programmers.

• Take a story from start to finish, or in other words: from planning to coding, to testing, to done.

• Take breaks when you want.

• A session should span an entire workday.

More ideas

These guidelines have worked for some teams, but they're not as structurally important.

• 4-5 people per session.

• Hold regular retrospectives.

• Use this time as an opportunity to train.

• Invite "spectators" and non-dev stakeholders, but make sure everyone has a reason to be there.

• Voluntary attendance; this won't work for everyone.

• Adjust often, as needed.