Tableau Exam Desktop-Specialist Topic 8 Question 10 Discussion

A parameter is a global placeholder value such as a number, date, or string that can replace a constant value in a calculation, filter, or reference line.

For example, you may create a calculated field that returns True if Sales is greater than $500,000 and otherwise returns False. You can replace the constant value of ''500000'' in the formula with a parameter. Then, using the parameter control, you can dynamically change the threshold in your calculation.

For example -

https://help.tableau.com/current/pro/desktop/en-us/parameters_create.htm