Here's why:

* DNA is the genetic material that carries instructions for building and maintaining an organism.

* Chromatin is the complex of DNA and proteins that makes up chromosomes.

* In its uncondensed form, chromatin looks like a thin thread. It's during cell division that the chromatin condenses into the familiar X-shaped structures we call chromosomes.

So, when DNA is not condensed into chromosomes, it exists as chromatin, which has a thread-like appearance.