This document provides information about performing a red blood cell count. It discusses that red blood cells are biconcave discs around 8 micrometers in diameter. It describes how to perform a manual red blood cell count using a Neubauer chamber, diluted blood sample, and microscope. The steps include preparing a 1:200 dilution, filling the chamber, focusing on cells with the microscope, and counting cells within a specified area. The normal red blood cell count ranges for adults, newborns, and children are provided. Decreased red blood cell counts can indicate anemia, while increased counts can be seen with conditions like polycythemia or dehydration.