Cells "grown in LB broth to an OD600nm" > Cells "grown in LB broth to an OD600nm" What does the OD stand for in this?

**OD** = **O** ptical **D** ensity

As you grow cells in broth, the broth becomes cloudy. The more cells there are, the cloudier it is. After you grow your cells for a while, you can measure their progress by shining a light through your sample. The more light your cell culture absorbs (higher absorbance is equivalent to higher OD) the more cells there are in it.