Here's why:

* Chromatin is a complex of DNA and proteins that is found in the nucleus of eukaryotic cells. It's the "normal" state of DNA when the cell is not actively dividing.

* Chromosomes, the tightly packed structures we usually think of when discussing DNA, only form during cell division (specifically during mitosis and meiosis).

* Interphase is the period between cell divisions, and therefore, DNA exists as chromatin during this time.

Think of it like this:

* Chromatin is like a long, loose thread of yarn. It's accessible for the cell to read the genetic code and make proteins.

* Chromosomes are like that same thread of yarn, but tightly wound into a compact ball. This makes it easier to distribute the DNA equally to daughter cells during cell division.