How is Estimation Done in a Scrum Project?

The estimation of user stories is done based on their difficulty

A particular scale is used to assess the difficulty of the user stories. Some type of scales are :

* Numeric Sizing (1 - 10)
* T-shirt Sizes (S, M, L, XL…)
* Fibonacci Series (1, 2, 3, 5, 8…)
* Dog breeds (Great Dane, Chihuahua…)