Query String enables you to add query string variables that you can use in your app. You would define the query string variables and then utilize the parameters in the public embedded apps and different tasks like the input task.
You can have a look at how the query string is used in the article here. Here it is being utilised only with the input task.
Click ‘Add query string’, and define your keyword name and your keyword value. Click Save Query String.
The keyword value can be accessed in the app by using the formula: QUERYSTRING(“keyword name”).
Example: If you specify a keyword say ‘demo’ and its value as say “252.23”. The value can be accessed by using the formula ‘QUERYSTRING(“demo”)’.
To know how you can even pass data in microapp navigation using the Query String, refer this article here.