Task lists are a simple but effective way to organise the steps involved in completing a user story. They should be ordered in terms of sequence and represent a linear plan.

You can perform an initial task breakdown during or after kicking off a user story but the list is a living document and you may add/remove items as you learn more during development.

You can use a task list to swarm on a story and coordinate. A pair or individual can pick up an item list and check back in with the others as they finish work and need to pick up something else.

Task lists are also a useful prop to use in the daily standup to explain what has been achieved since last time and what is left.