It is the youngest month on the calender, originally there was only 10 months. Caesar
added in July(named after himself) to account for some of the days
outside of the calander. 28 days was all that was left for the last
month added. The Earth takes 365.25 days to complete an orbit around the
sun. Thus every 4 years we have to adjust that extra day adding it to
February and having a 29 days month.