When using the Input node, you capture a user's input in a variable (you create this variable, and can decide on what to call it). For example, if you ask the user to enter his first name, you may use the variable name FirstName to store the user’s input.
You can refer to these variables in other nodes in your flow by wrapping it in double square brackets: [[Variable Name]].
See the example below:
When completing the information required for a node, you might sometimes see the following icon:
Clicking on this icon brings up a panel named Variables & Shortcuts. This panel lists all variables that you have added in nodes across your flow. This serves as a shortcut when you want to refer to any of these variables in your current node.