What is trello ? how trello works? how to work in trello?

What is trello ? how trello works? how to work in trello ?
can anyone let me know about it .
Please help me to complete my assignment.

@allwindowsapps
1- Trello is a web-based Kanban-style list-making application which is a subsidiary of Atlassian.
2- Create an account, and play for 10/15 minutes by just drag & drop

In short, It’s used to track tasks.
I suggest a short video https://www.youtube.com/watch?v=xky48zyL9iA