How burndown chart works?

[Omar Jouda]

I am currently working with burndown charts and try to track team progress .. however burndown charts somehow not clear for me

When exactly the line goes down for burndown charts? based on complete tasks or how exactly?

If someone can explain it simply I will be glad 

Thanks

[Nic Brough -Adaptavist-]

Burndown measures what you committed to doing in the sprint against what you complete during the sprint.  

It works off an estimate on the story (the committed items).  The burn-down for each story happens when you tell Jira that the story is "done", by moving the story into the last column on the board.

So when you look at a burn-down chart, you will see a line that goes left-to-right as you go through time, dropping down towards the x axis, over time, with each drop being caused by moving a story to the last column, and the drop being proportional to the size of the estimate on the story you've completed.