How to work with asynchronous events?

[SimonLab]

We can use async, await keywords and the class Future to manage asynchronous operation. For example when retrieving data from an API the returned values might take a bit of time depending on the API server, network status...

• [x] Read https://dart.dev/codelabs/async-await and summarise how to manage asynchronous events
• [x] The keyword then is also sometimes used with asynchronous function, what is the difference with async/await and then