Sanity Testing: Testing conducted to judge the build for furthur regression testing is called Sanity Testing.
1) While accepting the build for regression testing, Sanity is conducted.
2) Sanity can be conducted on daily/weekly basis to ensure build stability. this is called Health Check only 1 flow or Scenario is considered per day
Sanity is more of cursory testing hence authoring test cases is not desired. Just pick up a scenario and proceed with tester intitution.