You have 3 billion bases in your DNA on 46 chromosomes (and 2 sex chromosomes), and if you stretched out, it would be 2m long! So how can it fit into your cells?
Your cells package the DNA, allowing it to access the pieces that it needs to read the instructions needs. The rest is compressed by creating coils upon coils.
The most intense compression occurs when a cell is ready to divide. At this time, it is compressed into a familiar shape that we call a CHROMOSOME. This chromosome is one molecule of DNA, compressed into a small bar. When the cell makes a copy of the DNA (so that there’s a copy for each of the two daughter cells that will result from division), it forms an X shape, connected at the middle by a point called the CENTROMERE.
It’s this X shape that is the hallmark of a cell actively going through the motions of MITOSIS, or cell division.