Topics: Karyotype - Wikipedia
A karyotype is the number and appearance of chromosomes in the nucleus of a eukaryotic cell. The term is also used for the complete set of chromosomes in a species or in an individual organism    and for a test that detects this complement or measures the number.
Karyotypes describe the chromosome count of an organism and what these chromosomes look like under a light microscope. Attention is paid to their length, the position of the centromeres , banding pattern, any differences between the sex chromosomes , and any other physical characteristics.  The preparation and study of karyotypes is part of cytogenetics.
The study of whole sets of chromosomes is sometimes known as karyology. The chromosomes are depicted (by rearranging a photomicrograph) in a standard format known as a karyogram or idiogram : in pairs, ordered by size and position of centromere for chromosomes of the same size.