Each chromosome is made from a single molecule of DNA, but when a cell is ready to divide, the DNA copies itself, then coils and condenses to form the chromosomes that we see in micrographs.
Each human body cell contains 46 chromosomes. These can be arranged into 23 pairs.
Each chromosome in a pair carries the same genes. One chromsome was inherited from the organism's mother, and is known as the maternal chromosome, and the other chromsome in the pair was inherited from the organism's father, and is known as the paternal chromosome.
The 23rd pair is the sex chromosomes. In females, the two chromosomes are identical in shape. There are two X chromosomes. Females are referred to as XX.
In males, one of the sex chromosomes is a different shape. There is an X and also a Y chromosome. Males are referred to as XY.