The day side ionosphere of Venus is primarily the product of solar photoionization of the planetary neutral atmosphere and subsequent photochemical processes. Its major characteristics are the main layer V2 and the underlying smaller V1 layer. While V2 is in general produced by solar radiation (extreme ultraviolet), the V1 layer is primarily produced from solar X-ray photoionization and secondary impact ionization of photo-electrons. O2+ yields the highest ion density in the main peak altitude range while at higher altitudes O+ dominates. VeRa observations from 2004 to 2014 show the day side maximum of V2 at altitudes from 135 km to 145 km. The V2 electron density in the VeRa observations varies from 15e10 to 55e10 electrons/m3 as a function of the solar radiation incidence angle and solar activity. Information on additional properties of the Venus ionosphere in comparison with Mars can be found here.