Note: this site last updated in 2006
An article from "The Molecules of HIV" (c) Dan Stowell
The Angstrom (or, more properly, the Ångström) is a measure of length equal to one-hundred-millionth of a centimetre. It's very handy for talking about sizes of molecules. A water molecule - for example - is roughly 3 Ångström in size.
This unit of measurement is named after the Swedish physicist Anders Jonas Ångström. Note that it's a unit of length, not of weight or mass (as opposed to the kiloDalton, which you may often see used to describe a protein's size.)