Volumetric Flask:
Volumetric glassware has been calibrated to have an accurate volume by taking the mass of 100 grams of H2O and then marking the point that equals the correct volume. This is in contrast to beakers and graduated cylinders which are marked by a machine.
When conducting experiments where the volume must be accurately measured, it is much better practice to use volumetric glassware where standard solutions are being prepared.
Volumetric glassware should not be in contact with a strong base for any extended period. This will corrode a layer of glass and change the volume otherwise.