That's a good question! While chromosomes are most visible during cell division, they are present in the cell throughout its life cycle.

Here's why they are only visible during division:

* Chromatin Structure: Most of the time, chromosomes exist as long, thin strands of DNA called chromatin. This chromatin is dispersed throughout the nucleus and is not easily visible under a light microscope.

* Condensation: During cell division, the chromatin undergoes a process called condensation. This process packs the DNA tightly into compact structures, making the chromosomes much thicker and easier to see.

* Purpose of Condensation: The condensation of chromosomes is crucial for the accurate distribution of genetic material to the daughter cells during cell division.

So, while chromosomes are not always "visible" in the sense of being observable under a light microscope, they are always present within the cell nucleus.