A karyotype isn't detailed enough to tell you about the individual genes on a chromosome, but it can tell you whether the chromosomes as a whole are in working order and it may help doctors diagnose and understand diseases. The members of a pair are the same size and shape, and they have the same banding patterns. In other words, each person actually possesses two copies of chromosome 1, two copies of chromosome 2, and so on. Human cells contain 23 pairs of chromosomes. Humans have 22 pairs of autosomes.
Many organisms also have a pair of sex chromosomes, which differ between males and females.
In humans, a female has two identical sex chromosomes. A male has one sex chromosome that is like those of females, and one that is smaller and differently shaped. The sex chromosomes of many other species have a similar pattern, but it is not the only possibility.