Angstrom is the unit of the length which is equal to one ten-billionth of the metre or 10⁻¹⁰ m. It is represented by the symbol is Å .
Angstrom is not part of SI system of the units, but it is considered as a part of metric system.
Angstrom is used often in natural sciences as well as technology in order to express the sizes of atoms / molecules, and the lengths of the chemical bonds, etc.