​Chromatid

So what's a chromatid? Well, during DNA division, when a cell divides, it needs to take its DNA and duplicate it and then transfer half of it to one cell and half to the other cell. Well, DNA's arranged in chromosomes, as you know, so what happens is, as a chromosome replicates, or makes a copy of itself, it's arranged as two chromosomes next to each other, called chromatids. Then during mitosis, when the DNA is transferred to the two daughter cells, one of each of those chromatids is transferred to each of the two cells. So a chromatid is one copy of a chromosome after DNA replication.