This is a unique identifier name for the RatingBar so you can refer to the RatingBar later in your project.
1. Add a Rating Bar in your main.xml file.
2. In the main.xml file, add the code below between the RatingBar tags.This will name the RatingBar myRatingBar.
android:id = "@+id/myRatingBar"
3. The "+" character is required if you have not yet defined that id, if perhaps the element you reference is lower in the .xml file.
Otherwise you if it's already defined above (or included) then you can omit the "+" char:
4. Compile and run!
Next Recommended Article: How to Declare a RatingBar