What is a karyotype and what is it used for?

A karyotype is a a picture to show the appearance and number of chromosomes to determine whether you have a disease caused by a genetic mutation (sickle cell anemia, down’s syndrome). It can also tell gender.
For example, if you see an extra chromosome in the 23rd pair, you can tell it’s down syndrome.
Two XX’s in the karyotype can tell you that you are a girl, and XY can tell that you are a boy.
Hope this helped!